RANDOM LIBRARY AGREEMENT


     This RANDOM LIBRARY AGREEMENT (the "Agreement"), effective as of December 
31, 1995 (the "Effective Date"), is made by and between Pharmacopeia, Inc., a 
Delaware corporation having a principal place of business at 101 College 
Road East, Princeton, New Jersey 08540 ("Pharmacopeia"), and Bayer 
Corporation, an Indiana corporation having a principal place of business at 
400 Morgan Lane, West Haven, Connecticut 06516 ("Bayer").

                                  BACKGROUND

     A.   Pharmacopeia has developed novel proprietary methods for the 
generation of encoded compound libraries. Pharmacopeia believes that its 
proprietary technology, by rapidly producing diverse and targeted compound 
libraries, will accelerate the drug discovery process and increase 
productivity of drug discovery programs.

     B.   Bayer wishes to obtain from Pharmacopeia certain Bayer Random 
Libraries (as hereinafter defined) to be screened by Bayer against targets 
chosen by Bayer, and Pharmacopeia is willing to provide such Bayer Random 
Libraries to Bayer, on the terms and conditions set forth herein.

     C.   On even date herewith, Bayer and Pharmacopeia have entered into a 
Collaboration Agreement.

     D.   Bayer and Pharmacopeia are entering into a Stock Purchase Agreement, 
pursuant to which Bayer has agreed to purchase, and Pharmacopeia has agreed 
to sell to Bayer, shares of Pharmacopeia Common Stock.

     NOW, THEREFORE, for and in consideration of the covenants, conditions, 
and undertakings hereinafter set forth, it is agreed by and between the 
parties as follows:

                                   ARTICLE 1
                                  DEFINITIONS

     1.1 "ACTIVE COMPOUND" shall mean a Library Compound that Bayer (or its 
designee) designates pursuant to Section 2.5 herein.

     1.2  "AFFILIATE" shall mean any corporation or other business entity 
which during the term of this Agreement controls, is controlled by or is 
under common control with Pharmacopeia or Bayer but only for so long as such 
entity controls, is controlled by, or is under common control with 
Pharmacopeia or Bayer. For this purpose, control means the possession of the 
power to direct or cause the direction of the management and the policies of 
an entity whether through ownership directly or

<PAGE>

indirectly of fifty percent (50%) or more of the stock entitled to vote, and 
for non-stock organizations, the right to receive over fifty percent (50%) of 
the profits by contract or otherwise, or if not meeting the preceding 
requirements, any company owned or controlled by or owning or controlling 
Pharmacopeia or Bayer at the maximum control or ownership right permitted in 
a country where such company exists.

     1.3  "AGREEMENT COMPOUND" shall mean any Active Compound or Derivative 
Compound. Agreement Compounds shall not include Excluded Products.

     1.4  "AGREEMENT PRODUCT" shall mean any product, including bulk active 
ingredients, containing an Agreement Compound, except Excluded Products.

     1.5  "BAYER RANDOM LIBRARY" shall mean any chemical compound library 
prepared by or on behalf of Pharmacopeia containing compounds based on 
structures selected by Pharmacopeia, solely or with the guidance of the RSC, 
and transferred to Bayer pursuant to this Agreement.

     1.6  "BAYER TECHNOLOGY" shall mean any patent application filed after the 
Effective Date and before the Cutoff Date (or a division, continuation or 
continuation-in-part of any such patent application) or any patent issuing on 
any of the preceding including reissues or re-examinations, which is owned or 
controlled, in whole or part, by Bayer or its Affiliates at any time during 
the term of this Agreement that claims the synthesis, composition of matter or 
method of use of a Library Compound or Agreement Compound.

     1.7  "COLLABORATION AGREEMENT" shall mean that certain Collaboration 
Agreement of even date herewith entered by and between Pharmacopeia and Bayer.

     1.8  "COLUMBIA LICENSE" shall mean that certain License Agreement 
effective as of July 16, 1993, as amended and restated as of October 6, 1995, 
entered by and between Pharmacopeia, Inc., the Trustees of Columbia 
University in the City of New York and the Cold Spring Harbor Laboratory.

     1.9  "CONSUMER PRICE INDEX" or "CPI" means the Consumer Price Index, All 
Urban Consumers, as published by the U.S. Bureau of Labor Statistics.

     1.10 "CUTOFF DATE" means the date, with respect to any Derivative 
Compound,  [ * * * ]  years following the designation of the Active 
Compound from which such Derivative Compound was derived.

     1.11 "DERIVATIVE COMPOUND" shall mean, with respect to compounds 
possessing activity against a specific molecular target, any compound derived 
by Pharmacopeia, Bayer, or its Affiliates or Sublicensees, or a third party 
under authority from Bayer, from a Library Compound. As used herein, a 
compound shall be deemed

[ * * *  Confidential Treatment Requested. ]


                                      -2-

<PAGE>

to have been "derived from" a Library Compound if it,  [ * * * ]  . It is 
understood that "Derivative Compound" shall include any compound derived from 
a Library Compound or from another Derivative Compound. It is further 
understood that Derivative Compound shall not include compounds "derived 
from" Excluded Products.

     1.12 "DEVELOPMENT CANDIDATE" shall have the meaning set forth in Section 
4.2.4.

     1.13 "EXCLUDED PRODUCT" shall mean any product which contains:

          (i)   a Library Compound which is screened by Bayer, which  
compound existed in Bayer's in-house chemical sample collection, as shown by 
contemporaneous documentation, prior to the RSC's selection of the initial 
Bayer Random Library containing such Library Compound or the RSC's 
commencement of the design of a Bayer Random Library containing such Library 
Compound, as the case may be; or

          (ii)  any Derivative Compound having activity against the same 
specific molecular target as an Active Compound, which Derivative Compound is 
conceived and synthesized by Bayer or its Affiliates after the Cut-off Date 
of such Derivative Compound; or

          (iii) a compound, other than a Derivative Compound, conceived 
and synthesized by Bayer or its Affiliates or by a third party under the 
authority of Bayer, independently of the intellectual property developed 
through the activities set forth in subsections (i)-(iii) of Section 1.11, as 
shown by contemporaneous documentation; or

          (iv)  any Derivative Compound which Bayer incorporates into its 
in-house chemical sample collection, and

                (a)  which is determined by Bayer or its Affiliates to have 
biological activity with respect to any additional target against which no 
Library Compound was screened, and which Bayer elects to commercialize solely 
for use with respect to such additional target, or

                (b)  which is determined by Bayer or its Affiliates to 
have biological activity with respect to a target against which no Library 
Compound displayed any activity, and which Bayer elects to commercialize 
solely for use with respect to such target.

[ * * *  Confidential Treatment Requested. ]


                                      -3-

<PAGE>

     1.14  "EXCLUDED TECHNOLOGY" means any intellectual property owned or 
licensed by Pharmacopeia and its Affiliates relating to the creation or use 
of encoded combinatorial libraries, tag and/or marker compound engineering 
and encoding, proprietary database and computational technology and/or high
throughput screening assays.

     1.15  "EXCLUSIVITY PERIOD" shall mean:

           (i)  with respect to all Library Compounds contained in any Bayer 
Random Library supplied to Bayer pursuant to Section 2.1 below, that period 
commencing on the date Pharmacopeia provides Bayer notice that all compounds 
of any such Library are available to be shipped to Bayer (the "Notice Date") 
and continuing until  [ * * * ]  of the Notice Date, or such later date as 
may be established under Section 2.4 below; and

           (ii)  for Active Compounds originating in such a library, for so 
long as Bayer (or its Affiliates or Sublicensees) are using diligent efforts 
as set forth in Section 6.1 to actively develop and commercialize a 
particular Agreement Product based on such Active Compound.

     1.16  "FDA" means the U.S. Food and Drug Administration or any 
corresponding foreign registration or regulatory authority.

     1.17  "IND" shall mean an Investigational New Drug application, as 
defined in the U.S. Food, Drug and Cosmetic Act and the regulations 
promulgated thereunder for initiating clinical trials in the United States, 
or any corresponding foreign application, registration or certification.

     1.18  "INITIAL TERM" shall have the meaning set forth in Section 1.18 of 
the Collaboration Agreement.

     1.19  "LEAD COMPOUND" shall have the meaning set forth in Section 4.2.3 
below.

     1.20  "LIBRARY COMPOUND" shall mean any compound which is or was 
contained in a Bayer Random Library.

     1.21  "LICENSED TECHNOLOGY" shall mean Existing Patent Rights, Future 
Patent Rights, Existing Know-How and Future Know-How. It is understood that 
the Licensed Technology shall not include the Excluded Technology.

           1.21.1  "EXISTING PATENT RIGHTS" shall mean (i) all patents and 
patent applications existing as of the Effective Date that claim any Active 
Compound or Derivative Compound, or method of use or process for the 
synthesis thereof or

[ * * *  Confidential Treatment Requested. ]


                                     -4-


<PAGE>

composition-of-matter thereof, and (ii) any divisions, continuations, 
continuations-in-part, reissues, reexaminations, extensions or other 
governmental actions which extend any of the subject matter of the patent 
applications or patents in (i) above, and any substitutions, confirmations, 
registrations, revalidations, or additions of any of the foregoing, in each 
case, which is owned or controlled, in whole or part, by license, assignment 
or otherwise by Pharmacopeia during the term of this Agreement, and subject 
to any limitations and prohibitions of such license or sublicense.

          1.21.2  "FUTURE PATENT RIGHTS" shall mean (i) all patents and 
patent applications claiming an Active Compound or Derivative Compound or 
method of use or process for the synthesis thereof conceived and reduced to 
practice by Pharmacopeia in the period from the Effective Date until the 
expiration of the last to expire Exclusivity Period of the Bayer Random 
Libraries provided hereunder; and (ii) any divisions, continuations, 
continuations-in-part, reissues, reexaminations, extensions or other 
governmental actions which extend any of the subject matter of the patent 
applications or patents in (i) above, and any substitutions, confirmations, 
registrations, revalidations, or additions of any of the foregoing, in each 
case, which is owned or controlled, in whole or part, by license, assignment 
or otherwise by Pharmacopeia during the term of this Agreement.

          1.21.3  "EXISTING KNOW-HOW" shall mean all ideas, inventions, data, 
know-how, instructions, processes, formulas, expert opinion and information, 
including, without limitation, biological, chemical, pharmacological, 
toxicological, pharmaceutical, physical and analytical, clinical, safety, 
manufacturing and quality control data and information, existing as of the 
Effective Date, owned or controlled in whole or part by Pharmacopeia by 
license, assignment or otherwise, in each case, which is necessary for the 
development, manufacture, use or sale or commercialization of Agreement 
Products, in each case, to the extent Pharmacopeia has the right to license 
or sublicense the same, and subject to any limitations and prohibitions of 
such license or sublicense. Excluded from Existing Know-How are any 
inventions otherwise included in the Existing Patent Rights.

          1.21.4  "FUTURE KNOW-HOW" shall mean all ideas, inventions, data, 
know-how, instructions, processes, formulas, expert opinion and information, 
including, without limitation, biological, chemical, pharmacological, 
toxicological, pharmaceutical, physical and analytical, clinical, safety, 
manufacturing and quality control data and information, owned or controlled 
by Pharmacopeia, in whole or part, by license, assignment or otherwise in the 
period from the Effective Date until the expiration of the last to expire 
Exclusivity Period of the Bayer Random Libraries provided hereunder, in each 
case, which is necessary for the development, manufacture, use, sale or 
commercialization of Agreement Products. Excluded from Future Know-How are 
any inventions otherwise included in the Future Patent Rights.



                                    -5-


<PAGE>

     1.22  "MAJOR COUNTRY" shall mean any of the United States, Canada, 
Japan, the United Kingdom, France, Germany, Italy or Spain.

     1.23  "NDA" shall mean a New Drug Application, as defined in the U.S. 
Food, Drug and Cosmetic Act and the regulations promulgated thereunder, or 
any corresponding foreign application, registration or certification.

     1.24  "NET SALES" shall mean the invoice price of Agreement Products sold 
by Bayer or its Affiliates or Sublicensees to third parties, less, to the 
extent included in such invoice price the total of: (1) ordinary and 
customary trade discounts actually allowed; (2) credits, rebates and returns 
(including, but not limited to, wholesaler and retailer returns); (3) 
freight, postage, insurance and duties paid for and separately identified on 
the invoice or other documentation maintained in the ordinary course of 
business, and (4) excise taxes, other consumption taxes, customs duties and 
compulsory payments to governmental authorities actually paid and separately 
identified on the invoice or other documentation maintained in the ordinary 
course of business. Net Sales shall also include the amount or fair market 
value of all other consideration received by Bayer or its Affiliates or 
Sublicensees in respect of Agreement Products, whether such consideration is 
in cash, payment in kind, exchange or another form. In the case of pharmacy 
incentive programs, hospital performance incentive chargebacks, similar 
programs or discounts on "bundles" of products, Bayer may with notice to 
Pharmacopeia discount the bona fide list price of an Agreement Product by the 
average percentage discount of all Bayer products in a particular "bundle", 
calculated as follows:


                    Average percentage              A
                    discount on a          =   ------------  X 100
                    particular "bundle"             B


where A equals the total discounted price of a particular "bundle" of 
products, and B equals the sum of the undiscounted bona fide list prices of 
each unit of every product in such "bundle". Bayer shall provide Pharmacopeia 
documentation, reasonably acceptable to Pharmacopeia, establishing such 
average discount with respect to each "bundle". If an Agreement Product is 
not sold separately and no bona fide list price exists for such Agreement 
Product, the parties shall negotiate in good faith an imputed bona fide list 
for such Agreement Product.

     1.25  "NOTICE DATE" shall have the meaning set forth in Section 1.15 (i) 
of this Agreement.

     1.26  "PHASE I", "PHASE II", and "PHASE III" shall mean Phase I (or Phase 
I/II), Phase II (or Phase II/III), or Phase III clinical trials, 
respectively, in each case as prescribed by applicable FDA IND Regulations, 
or any corresponding foreign statutes, rules or regulations.



                                     -6-


<PAGE>

     1.27  "RESEARCH PROGRAM" shall have the meaning set forth in Section 2.1 
of the Collaboration Agreement.

     1.28  "RESEARCH PLAN" shall have the meaning set forth in Section 2.3 of 
the Collaboration Agreement.

     1.29  "RESEARCH STEERING COMMITTEE" OR "RSC" shall have the meaning set 
forth in Section 3.1 of the Collaboration Agreement.

     1.30  "SUBLICENSEE" shall mean with respect to a particular Agreement 
Compound or Agreement Product, a third party to whom Bayer has granted a 
sublicense or other right under the related Licensed Technology to make, have 
made, import, have imported, use and have used such Agreement Compound, or to 
make, have made, use, have used, import, have imported, offer for sale, have 
sold and/or sell such Agreement Product. As used in this Agreement, it is 
understood that "Sublicensee" shall also include (i) any third party to whom 
Bayer or a Bayer Affiliate has granted the right to distribute an Agreement 
Product, provided that such third party has the primary responsibility for 
marketing and promotion at its expense of such Agreement Product within the 
field or territory for which such distribution rights are granted, which 
marketing and promotional activities are not subsidized by Bayer, or (ii) any 
third party which uses or sells any Agreement Product under any direct or 
indirect grant of rights or authorization by Bayer or a Bayer Affiliate to 
have used or have sold such Agreement Product.

                                  ARTICLE 2
                                  LIBRARIES

     2.1  BAYER RANDOM LIBRARIES. Subject to the terms and conditions of this 
Agreement, during each year during the two (2) year period commencing on 
February 2, 1996, Pharmacopeia shall provide two (2) Bayer Random Libraries 
to Bayer for screening by Bayer. The Bayer Random Libraries shall be provided 
in  [ * * * ]  sets of plates (each set containing  [ * * * ]  copies of 
plates, sufficient to perform  [ * * * ]  assays in duplicate), in the format 
as set forth on Exhibit A. The initial Bayer Random Library will be provided 
to Bayer from Pharmacopeia's collection of Bayer Random Libraries, and shall 
be selected by the RSC based on Pharmacopeia's description of such Bayer 
Random Libraries, pursuant to the procedure as set forth in the Research 
Plan. The remaining Bayer Random Libraries subject to this Agreement shall, 
at the RSC's discretion and direction, be either designed solely by 
Pharmacopeia or with guidance from the RSC; provided, however, the design of 
such Bayer Random Libraries must be technically feasible, as reasonably 
determined by Pharmacopeia. As used herein, "technically feasible" means  
[ * * * ]  

[ * * *  Confidential Treatment Requested. ]


                                     -7-



<PAGE>

                                   [ * * * ]

     2.2  DELIVERY. The Bayer Random Libraries shall be available for 
delivery to Bayer as soon as practicable and if technically feasible no later 
than  [ * * * ]  or such other time as the parties may agree.  [Deliveries of 
plates, rearrays and decodes shall all be subject to the terms set forth on 
Exhibit A.



     2.3  EXCLUSIVITY PERIODS. The Bayer Random Libraries provided to Bayer 
hereunder shall not have been provided to third parties or screened by 
Pharmacopeia for third parties before delivery to Bayer, and shall not 
contain compounds contained in any other Bayer Random Library. To provide 
Bayer a period of exclusivity for screening of the Bayer Random Libraries, 
Pharmacopeia agrees that until the termination of the Exclusivity Period for 
a Bayer Random Library, as such period may be extended, Pharmacopeia shall 
not deliver to any third party a compound library containing compounds within 
such Bayer Random Library and shall not itself use such Bayer Random 
Libraries, except as permitted pursuant to Section 3.5, or as approved by 
Bayer in writing.

     2.4  ANNUAL EXTENSIONS OF EXCLUSIVITY PERIOD.

          2.4.1  RIGHT TO EXTEND. With respect to Bayer Random Libraries 
delivered to Bayer pursuant to Section 2.1, Bayer shall have the right to 
extend the Exclusivity Period with respect to any particular Bayer Random 
Library  [ * * * ]  by notifying Pharmacopeia no later than sixty (60) days 
prior to the date on which such Exclusivity Period will expire, and 
concurrently paying to Pharmacopeia a maintenance fee of  [ * * * ]  per year 
for each such Bayer Random Library. Such maintenance fee shall be fully 
creditable against any milestones paid by Bayer to Pharmacopeia with respect 
to Agreement Compounds (including Derivative Compounds) originating from such 
Bayer Random Library.

          2.4.2  LOSS OF RIGHTS. After the end of the Exclusivity period with 
respect to any Bayer Random Library, Bayer shall have no further rights with 
respect to that Bayer Random Library or any Library Compounds included 
therein except those Library Compounds designated as Active Compounds 
pursuant to Section 2.5 below during the applicable Exclusivity Period, 
except as provided in (a) below, or as Bayer and Pharmacopeia may otherwise 
agree.

                 (a) It is understood that after the Exclusivity Period of a 
Bayer Random Library, as such period may be extended, Pharmacopeia and Bayer 
may each subsequently use such Bayer Random Library, and Pharmacopeia may 
provide such Bayer Random Library to others, subject to the terms and 
conditions set forth in

[ * * *  Confidential Treatment Requested. ]


                                     -8-


<PAGE>

this Agreement. It is understood that either Pharmacopeia or Bayer may seek 
patent rights on its sole behalf with respect to any Library Compound which 
such party determines has patentable utility, provided that such Library 
Compound is (i) not an Active Compound and not within the scope of a patent 
application or patent within the Licensed Technology or Bayer Technology, or 
(ii) is an Active Compound with respect to which Bayer has not met the 
diligence requirements set forth in Section 6.1, and has not retained rights 
pursuant to Section 6.2.

                 (b) In the event that Pharmacopeia determines that any 
Library Compound which is not an Active Compound and which is claimed in a 
Bayer patent application or patent claiming an Active Compound has a 
biological activity distinct from the utility claimed in such patent 
application or patent, and does not have the utility claimed by Bayer, 
Pharmacopeia may provide Bayer with evidence reasonably demonstrating that 
such Library Compound does not have the utility claimed by Bayer. Bayer shall 
have a period of 90 days from receipt of such notice in which to provide 
Pharmacopeia with evidence reasonably demonstrating that such Library 
Compound has the utility claimed in the patent application or patent. In the 
event that Bayer fails to provide such evidence, Bayer and its Affiliates 
agree to grant and hereby grants to Pharmacopeia, an exclusive, worldwide, 
royalty-free license, with the right to grant and authorize sublicenses, 
under any applicable Joint Inventions and Bayer Technology necessary to make, 
have made, use, have used, import, have imported, sell, have sold and offer 
for sale such Library Compound or products based thereon.

     2.5  RIGHT TO DESIGNATE ACTIVE COMPOUNDS. Except with regard to Excluded 
Products, it is understood that Bayer or its Affiliates or Sublicensees may 
not develop or commercialize any Library Compound or any Derivative Compound 
developed from a Library Compound, unless such Library Compound has been 
designated as an Active Compound. Bayer shall have the right to designate any 
Library Compound in such Bayer Random Library as an Active Compound as 
follows.

          2.5.1  DECODING BY PHARMACOPEIA. At such time as Pharmacopeia has 
identified the structure of a Library Compound with activity in a particular 
biological assay to Bayer following a request for decoding by Bayer, that 
compound shall automatically be designated an Active Compound.

          2.5.2  IDENTIFICATION BY BAYER. In the event that Bayer or its 
Affiliates or Sublicensees identifies, without decoding by Pharmacopeia 
pursuant to Section 2.7 below, a particular Library Compound with activity in 
a particular biological assay, Bayer shall give Pharmacopeia notice 
identifying such Library Compound and indicating that it wishes to designate 
such Library Compound as an Active Compound. Such Library Compound shall be 
designated an Active Compound as of the date of Pharmacopeia's receipt of 
such notice.


                                     -9-

<PAGE>

     2.6  REARRAYS. During the Exclusivity Period of a particular Bayer 
Random Library, as it may be extended, and for six (6) months thereafter at 
Bayer's request, Pharmacopeia shall  [ * * * ]  rearray (at one compound per 
well) up to  [ * * * ]  wells identified by Bayer in the initial  [ * * * ]  
sets of plates. In the event that Bayer requests further rearrays during such 
period, Pharmacopeia agrees to perform such tasks at a cost of  [ * * * ]  
per additional rearray. In the event that Bayer requests further rearrays 
after the foregoing period, and Pharmacopeia agrees to perform such rearrays, 
the cost of each such rearray shall increase as set forth in Section 2.13. 
Pharmacopeia shall invoice Bayer for any such costs subject to this Section, 
and Bayer shall pay such invoice within thirty (30) days of receipt.

     2.7  DECODING. During the Exclusivity Period of a particular Bayer 
Random Library, as it may be extended, and for six (6) months thereafter, at 
Bayer's request, Pharmacopeia shall  [ * * * ]  decode up to  [ * * * ]  
active structures in the initial  [ * * * ]  sets of plates. In the event 
that Bayer requests further decodes during such period, Pharmacopeia agrees 
to perform such tasks at a cost of  [ * * * ]  per additional structure 
decoded. In the event that Bayer requests further decodes after the foregoing 
period, and Pharmacopeia agrees to perform such decodes, the cost of each 
decode shall be increased as set forth in Section 2.13. Pharmacopeia shall 
invoice Bayer for any such costs subject to this Section, and Bayer shall pay 
such invoice within thirty (30) days of receipt.

     2.8  SYNTHESIS.  [ * * * ]  Bayer may request that Pharmacopeia 
synthesize up to  [ * * * ]  of up to  [ * * * ]  Active Compounds from the 
initial  [ * * * ]  sets of plates for each Bayer Random Library subject to 
Section 2.1 above, and Pharmacopeia shall deliver such material to Bayer 
within sixty (60) days after a written request therefor; provided, 
Pharmacopeia shall have no obligation to synthesize an aggregate of more than 
[ * * * ]  compounds per month.

     2.9  ADDITIONAL COPIES OF LIBRARIES.

          2.9.1  UNTIL THE FIRST ANNIVERSARY OF THE NOTICE DATE. Until the 
first anniversary of the Notice Date of a particular Bayer Random Library, 
Bayer may provide Pharmacopeia notice that Bayer wishes to obtain one or more 
additional samplings of a particular Bayer Random Library for further 
screening, and Pharmacopeia will deliver plates containing such sampling to 
Bayer as soon as practicable. Bayer shall pay Pharmacopeia  [ * * * ]  for 
each additional set of plates (i.e.,  [ * * * ]  suitable for one additional 
assay). Pharmacopeia shall invoice Bayer for such costs, and Bayer shall pay 
such invoice within thirty (30) days of receipt. At Bayer's request  
[ * * * ] , for each set of plates Pharmacopeia shall rearray up to  [ * * * ]
wells in such set of plates, decode up to  [ * * * ]  active structures 
that demonstrate activity against any of the targets in Bayer's screening 
assays, and resynthesize up to  [ * * * ]  of  [ * * * ]  Active Compound. In 
the event that Bayer requests further

[ * * *  Confidential Treatment Requested. ]


                                  -10-


<PAGE>


decodes or rearrays, Pharmacopeia agrees to perform such tasks at cost of  
[ * * * ]  per additional rearray and  [ * * * ]  per additional structure 
decoded. Pharmacopeia shall invoice Bayer for any such costs, and Bayer shall 
pay such invoice within thirty (30) days of receipt.

          2.9.2  AFTER THE FIRST ANNIVERSARY OF THE NOTICE DATE. After the 
first anniversary of the Notice Date, until  [ * * * ]  after the Notice Date 
of a particular Bayer Random Library, Bayer may provide Pharmacopeia notice 
that Bayer wishes to obtain  [ * * * ]  additional samplings of a particular 
Bayer Random Library for further screening, and Pharmacopeia will deliver 
plates containing any such sampling to Bayer as soon as practicable. Bayer 
shall pay Pharmacopeia  [ * * * ]  for each additional set of plates (i.e., 
two copies suitable for one additional assay); provided, if Pharmacopeia's 
costs of preparing plates decrease following the Notice Date as the result of 
cost-reducing process improvements (if any), Pharmacopeia agrees to reduce 
the fee to provide Bayer the benefit thereof. However, Pharmacopeia shall not 
be obligated to provide any such plates to Bayer  [ * * * ]  Pharmacopeia 
shall invoice Bayer for such costs, and Bayer shall pay such invoice within 
thirty (30) days of receipt. At Bayer's request  [ * * * ]  for each set of 
plates Pharmacopeia shall rearray up to  [ * * * ]  wells in such set of 
plates, decode up to  [ * * * ]  active structures that demonstrate activity 
against any of the Bayer Targets in Bayer's screening assays and resynthesize 
up to  [ * * * ]  of  [ * * * ]  Active Compound. In the event that Bayer 
requests further decodes or rearrays, Pharmacopeia agrees to perform such 
tasks at a cost of  [ * * * ]  per additional rearray and  [ * * * ]  per 
additional structure decoded. Pharmacopeia shall invoice Bayer for any such 
costs, and Bayer shall pay such invoice within thirty (30) days of receipt.

    2.10  REPORTS. During the term of this Agreement, Bayer shall provide 
Pharmacopeia with written semi-annual reports within thirty (30) days of the 
end of each six (6) month period providing at least the following information 
regarding the status of all Agreement Compounds: (i) identification on a 
coded basis, of all targets against which each Agreement Compound 
demonstrated activity (i.e., with targets designated by an identification 
number selected by Bayer); (ii) description of the status of research and 
development activities conducted with respect to each target relating to 
Agreement Compounds; and (iii) the status of all patent applications claiming 
such Agreement Compounds. Such reports shall contain sufficient information 
to allow Pharmacopeia to monitor Bayer's compliance with this Agreement, 
including without limitation, Bayer's obligations with respect to due 
diligence and the accomplishment of the milestones set forth in Section 4.2 
below. Until first commercial introduction of each royalty-bearing Agreement 
Product by or on behalf of Bayer hereunder, Bayer shall keep Pharmacopeia 
apprised of the status of the pre-clinical, clinical and commercial 
development of that Agreement Product by semi-annually providing Pharmacopeia 
with a written report detailing such activities with respect to each 
applicable Agreement Product during the term of this Agreement. All reports 
and

[ * * *  Confidential Treatment Requested. ]


                                  -11-


<PAGE>


information provided under this Section 2.10 shall be deemed Confidential 
Information of Bayer.

    2.11  TECHNOLOGY TRANSFER. Subject to Section 3.7 below, to maximize the 
success of the Research Program, Pharmacopeia and Bayer shall exchange 
agreed information and materials relating to solid-phase chemical synthesis; 
provided, Pharmacopeia shall have no obligation to disclose to Bayer any 
materials or information relating to the Excluded Technology.

    2.12  RETAINED RIGHTS. Pharmacopeia shall retain ownership of the 
tangible property embodied in the physical Bayer Random Libraries and the 
Library Compounds therein provided to Bayer hereunder. It is understood that 
Bayer shall have certain license and patent rights with respect to such 
Library Compounds under this Agreement.

    2.13  CPI ADJUSTMENT. Beginning six (6) months after the  [ * * * ]  of 
the Notice Date of a particular Bayer Random Library, the charges for 
rearrays and decoding set forth in Sections 2.6 and 2.7, respectively, shall 
annually increase to reflect the cumulative increase in the CPI, using 1996 
as the base date.

                               ARTICLE 3
                               LICENSES

    3.1   LICENSE TO BAYER. Subject to the terms and conditions of this 
Agreement, Pharmacopeia agrees to grant, and hereby grants to Bayer and its 
Affiliates an exclusive, worldwide license under the applicable Licensed 
Technology, to make, have made, import, have imported, use and have used 
Agreement Compounds, and to make, have made, import, have imported, use, have 
used, offer for sale, have sold and sell Agreement Products. It is understood 
that such licenses shall include the right to discover and develop Agreement 
Compounds and Agreement Products and to conduct drug research during the term 
of this Agreement.

    3.2   SUBLICENSES. Subject to their terms and conditions of this 
Agreement, Bayer (but not its Affiliates) shall have the right to sublicense 
the rights granted in Section 3.1 above; provided, Bayer shall not transfer 
any Bayer Random Library to any third party. Each sublicense granted by Bayer 
shall be consistent with all the terms and conditions of this Agreement and 
the Columbia License, and subordinate thereto, and Bayer shall remain 
responsible to Pharmacopeia for the compliance of each such Sublicensee with 
the financial and other obligations due under this Agreement. Such 
Sublicensees shall not have the right to grant further sublicenses, or grant 
third parties the right to have used or have sold the Agreement Compounds or 
Agreement Products, and such sublicenses may not be assigned or transferred 
to any third party without the prior written consent of Pharmacopeia. 
Promptly following the execution of

[ * * *  Confidential Treatment Requested. ]


                                  -12-


<PAGE>


any sublicense, Bayer shall notify Pharmacopeia of the existence and identity 
of each Sublicensee.

     3.3  THIRD PARTY RIGHTS:

          3.3.1  OVERLAPPING RIGHTS. Its is understood that Pharmacopeia is 
in the business of providing combinatorial libraries to third parties, and 
that Pharmacopeia will grant such third parties rights after the Effective 
Date to acquire licenses for compounds derived from such libraries similar to 
Bayer's rights under this Article 3. Notwithstanding the licenses granted 
above, it is possible that a third party may acquire rights from Pharmacopeia 
with respect to one or more compounds of which Pharmacopeia is a sole or 
joint owner; accordingly, Pharmacopeia's grant of rights in this Article 3 is 
limited to the extent that (i) a third party (either alone or jointly with 
Pharmacopeia) has filed a patent application with respect to such a compound 
prior to the filing by Bayer (either alone or jointly with Pharmacopeia) of a 
patent application with respect to such a compound, or (ii) Pharmacopeia has 
previously granted a third party a license or other rights with respect to 
such a compound, and subject to any such grant of rights to a third party.

          3.3.2  NO LIABILITY. It is understood and agreed that, even if 
Pharmacopeia complies with its obligations under this Agreement, compounds 
provided to third parties in the course of Pharmacopeia's other business 
activities may result in third party patent applications and patents, 
including patent applications and patents owned by such third parties, or 
owned jointly by Pharmacopeia and such third parties, which could conflict 
with patent applications and patents owned by Bayer, or jointly owned by 
Bayer and Pharmacopeia hereunder. Pharmacopeia will use its reasonable 
efforts to avoid such conflict and, unless Bayer is damaged as a proximate 
result of a material breach by Pharmacopeia of the terms of Article 2 or any 
of the representations and warranties in Article 9, then Pharmacopeia shall 
have no liability under this Agreement with respect to any such conflict.

     3.4  COLUMBIA SUBLICENSE. Subject to the terms and conditions of this 
Agreement and the Columbia License, if necessary, Pharmacopeia will grant to 
Bayer and its Affiliates and directly to Bayer's Sublicensees a 
non-exclusive, worldwide sublicense, without the right to sublicense, under 
the Columbia License, to make, have made, import, have imported, use and have 
used Agreement Compounds, and make, have made, import, have imported, use, 
have used, offer for sale, have sold and sell Agreement Products. It is 
understood and agreed that such sublicenses do not include the right to 
create, make or have made encoded combinatorial libraries, tags, markers or 
other encoding compositions, or use methods or processes relating to encoded 
combinatorial libraries, tags, markers, or other encoding compositions, 
except as expressly provided in this Agreement. In the event the Columbia 
License is terminated, Bayer may become a licensee under the Columbia License, 
to the extent and by the procedure provided for in the Columbia License.

                                    -13-


<PAGE>


     3.5  RESEARCH LICENSE. Notwithstanding Section 3.1 above, Pharmacopeia 
shall retain the right under the Licensed Technology to make, have made and 
use Library Compounds for its own research purposes (i.e., to develop, improve 
and validate its technology and intellectual property). Pharmacopeia agrees 
not to conduct research or have research conducted on its behalf pursuant to 
this Section which would adversely affect Bayer's ability to commercialize 
Agreement Compounds pursuant to this Agreement or which would jeopardize the 
commercial or research value of the Bayer Technology.

     3.6  NO PRODUCTS OTHER THAN AGREEMENT PRODUCTS. Except as otherwise 
agreed or specifically provided in the terms of this Agreement, neither Bayer 
nor its Affiliates or Sublicensees shall commercialize any Library Compound 
or Agreement Compound, other than as an Agreement Product in accordance with 
this Agreement.

     3.7  TECHNOLOGY TRANSFER. Each party hereby grants to the other a 
worldwide, non-exclusive, royalty-free license, with the right to grant 
sublicenses, to use for all purposes all information and materials 
transferred to the other pursuant to Section 2.11 above which is necessary 
for solid-phase synthesis of Bayer Random Libraries.

     3.8  BAYER AFFILIATES. Attached hereto as Exhibit B is a complete list 
of Bayer's Affiliates which shall have the right to practice the license 
rights granted in Section 3.1 above. Bayer Affiliates not listed on Exhibit 
B, as may be amended from time to time, shall not have the right to practice 
such licenses. During the term of the Agreement, Bayer may amend Exhibit B 
with notice to Pharmacopeia.

                                 ARTICLE 4
                                 PAYMENTS

     4.1  LIBRARY PREPARATION FEE. In consideration for the Bayer Random 
Libraries prepared for Bayer hereunder, Bayer agrees to pay to Pharmacopeia a 
fee of  [ * * * ]  for each Bayer Random Library subject to Section 2.1. The 
fee for each of the first two (2) Bayer Random Libraries is due on February 
12, 1996, and the fee for each of the second two (2) Bayer Random Libraries 
is due on  [ * * * ] . Such amounts shall not be refundable or creditable 
against any other amounts due Pharmacopeia under this Agreement.

[ * * *  Confidential Treatment Requested. ]

                                    -14-


<PAGE>


     4.2  MILESTONE PAYMENTS.

          4.2.1  MILESTONE PAYMENTS. Subject to Section 4.2.2 below, Bayer 
agrees to pay to Pharmacopeia the following amounts upon achievement by 
Bayer, or its Affiliates or Sublicensees or other designee of each of the 
following milestones with respect to Agreement Compounds (including Agreement 
Products), but not with respect to Excluded Products, as follows:



                 Milestone                             Amount
                 ---------                             ------
         Identification of Lead Compound               $

         Nomination of a Development Candidate         $
                                                       
         Filing of an IND or initiation of human       
         trials in any country                         $   *

         Initiation of Phase III clinical trials           *
         in any country                                $
                                                           *
         Filing of an NDA or NDA equivalent in a    
         Major Country                                 $

         First approval of an NDA or NDA equivalent
         in a Major Country                            $

                                              Total    $

     The payments set forth above shall be made with respect to each 
Agreement Compound; provided, however, if Bayer ceases all development of a 
particular Agreement Compound or Agreement Product after having made payments 
with respect to such Agreement Compound or Agreement Product under this 
Section 4.2.1 following the accomplishment of any milestone specified herein, 
there shall be no payment due upon the accomplishment of that same milestone 
with respect to any subsequent Agreement Compound or Agreement Product 
hereunder, directed at the same molecular target for the same indication. 
When milestones are achieved with respect to such subsequent Agreement 
Product which were not previously paid with respect to an earlier Agreement 
Compound or Agreement Product, such milestone payments shall be paid pursuant 
to this Section 4.2.1.

          4.2.2  EXCLUSIONS. Notwithstanding Section 4.2.1 above, in the 
event that a Derivative Compound which Bayer elects to develop (i)  [ * * * ] 
and (ii) is not (a) within the scope of a patent within the Licensed 
Technology, Joint Inventions, or Bayer Technology issued as of the Cutoff 
Date, or (b) within the scope of a patent within the Licensed Technology, 
Joint Inventions, or Bayer Technology issued from a

[ * * *  Confidential Treatment Requested. ]


                                   -15-

<PAGE>


patent application pending as of the Cutoff Date (or a division or 
continuation of such an application) and issued subsequent to the Cutoff 
Date, then Bayer shall not be obligated to pay to Pharmacopeia any milestone 
payments above respect to such Derivative Compound (or corresponding 
Agreement Product).

          4.2.3  LEAD COMPOUND. As used herein, a Lead Compound shall be 
deemed to have been identified at such time as Bayer by action of the Bayer 
International Research Committee ("IRC") or its successor approves a 
strategic project based on such Agreement Compound. In any event, however, if 
Bayer, or any Affiliate or Sublicensee or other designee commits five or more 
chemists to perform medicinal chemistry optimization with respect to a 
particular Agreement Compound, the milestone payment due upon identification 
of a Lead Compound corresponding to such Agreement Compound shall have been 
paid to Pharmacopeia. Within thirty (30) days after the earlier of the 
occurrence of (i) an IRC (or corresponding) approval, or (ii) the assignment 
of five chemists as set forth above, Bayer shall notify Pharmacopeia thereof.

          4.2.4  DEVELOPMENT CANDIDATE. As used herein, "Development 
Candidate" shall mean a Lead Compound or Derivative Compound therefrom which 
possesses the desirable properties of a therapeutic agent for the prevention 
or treatment of a clinical condition, in the absence of required safety 
trials necessary to begin testing in humans or animals. A Development 
Candidate shall have been deemed to have been nominated upon the date the  
[ * * * ]  of Bayer (or its successor) approves proceeding with full 
development of such Agreement Compound. It is understood and agreed that IN 
VIVO GLP toxicology trials necessary to initiate human clinical trials with 
respect to an Agreement Compound will not be initiated without the approval 
of the IPDC, which approval will be deemed to constitute nomination of a 
Development Candidate.

          4.2.5  NON-HUMAN USES. In the event that Bayer intends to develop 
or commercialize an Agreement Product for any uses other than human 
therapeutic or prophylactic uses, it shall promptly notify Pharmacopeia, and 
the parties shall negotiate in good faith milestone events and payments with 
respect to each such Agreement Product which, in each case, shall provide 
Pharmacopeia remuneration in accordance with the commercial value of such use.

          4.2.6  PAYMENTS DUE. All payments made to Pharmacopeia by Bayer 
pursuant to Section 4.2 shall be due within thirty (30) days after the 
achievement of the corresponding milestone and shall be nonrefundable.

[ * * *  Confidential Treatment Requested. ]


                                     -16-

<PAGE>

     4.3  ROYALTIES TO PHARMACOPEIA

          4.3.1  BASE ROYALTY.  Bayer shall pay to Pharmacopeia running 
royalties equal to  [ * * * ]  percent  [ * * * ]  of Net Sales made by Bayer 
and its Affiliates and Sublicensees of Agreement Products.

          4.3.2  EXCLUSIONS.  Notwithstanding Section 4.3.1 above, in the 
event that a Derivative Compound (or corresponding Agreement Product) which 
Bayer elects to develop (i) is conceived later than  [ * * * ]  after the 
designation of the Active Compound from which such Derivative Compound was 
derived, as shown by contemporaneous written evidence, and (ii) is not (a) 
within the scope of a patent within the Licensed Technology, Joint 
Inventions, or Bayer Technology issued as of the Cutoff Date, or (b) within 
the scope of a patent within the Licensed Technology, Joint Inventions, or 
Bayer Technology issued from a patent application pending as of the Cutoff 
Date (or a division or continuation of such an application) and issued 
subsequent to the Cutoff Date, then Bayer shall not be obligated to pay to 
Pharmacopeia any royalty payments with respect to such Derivative Compound 
(or corresponding Agreement Product).

          4.3.3  TRADE SECRET ROYALTIES.  The parties acknowledge and agree 
that the principal value contributed by Pharmacopeia is accelerated time to 
market, enhanced probability of success and the potential for multiple target 
leads, and that Pharmacopeia may not own or control patent applications or 
patents covering the manufacture, sale or use of a particular Agreement 
Product. Bayer acknowledges and agrees that the value Bayer receives 
hereunder is in the access to the Libraries and accordingly  Bayer shall pay 
the royalties at the rate specified in this Section 4.3, regardless of 
whether an Agreement Product is covered by a patent application or patent 
within the Licensed Technology, Joint Inventions or Bayer Technology unless 
in any country or countries in which Bayer or its Affiliates and/or 
Sublicensees are selling an Agreement Product, a third party which is not an 
Affiliate or Sublicensee of Bayer is selling a directly similar competing 
Agreement Product and sales of such third party(ies) directly similar 
competing Agreement Product constitute  [ * * * ]  percent  [ * * * ]  or 
more of the Net Sales of the Agreement Product in such country. In the event 
the above described conditions are met, the royalty rate shall equal  
[ * * * ]  percent  [ * * * ]  of the Net Sales of such Agreement Product in 
such country for the period in which such competing sales exceed  [ * * * ]  
percent  [ * * * ]  of the Net Sales in such country.

          4.3.4  ROYALTY TERM.  Bayer's obligation to pay royalties to 
Pharmacopeia under this Section 4.3 shall continue for each Agreement 
Product, on a country-by-country basis, until the date which is the later of 
(i)  [ * * * ]  after the first commercial sale of such Agreement Product in 
such country by Bayer, its Affiliates or Sublicensees, or (ii) the expiration 
of the last to expire issued patent within the Licensed Technology containing 
any claim which would be infringed by making, using 

[ * * *  Confidential Treatment Requested. ]


                                     -17-

<PAGE>

or selling the applicable Agreement Product in the applicable country in the 
absence of the license grants in this Agreement.

          4.3.5  SINGLE ROYALTY; NON-ROYALTY SALES.  No royalty shall be 
payable under this Section 4.3 with respect to sales of Agreement Products 
among Bayer; its Affiliates and Sublicensees for resale; and in no event 
shall more than one royalty be due hereunder with respect to any Agreement 
Product unit even if covered by more than one patent included in the Licensed 
Technology.

          4.3.6  THIRD PARTY ROYALTIES. Bayer shall be responsible for 
the payment of any royalties due to third parties for the manufacture, use, 
marketing, sale or distribution of Agreement Products by Bayer or its 
Affiliates or Sublicensees (except payments due pursuant to the Columbia 
License, which shall be the responsibility of Pharmacopeia). It is understood 
that Pharmacopeia shall be responsible for any royalties due third parties 
with respect to intellectual property required for the preparation of the 
Bayer Random Libraries or decoding of Library Compounds.

     4.4    EXCLUDED PRODUCT.  Until  [ * * * ] , years after the end of the 
last to expire Exclusivity Period of all Bayer Random Libraries, as such 
Exclusivity Periods may be extended, within thirty (30) days of the 
successful completion of Phase II clinical trials with respect to an Excluded 
Product, Bayer shall notify Pharmacopeia of such event, and provide a 
description of why such Excluded Product is not an Agreement Product 
hereunder; provided, Bayer shall have no obligation to notify Pharmacopeia or 
provide a description of any Excluded Product which does not contain a small 
molecule compound. If a dispute arises between the parties which the parties 
are unable to resolve regarding whether or not a product is an Excluded 
Product, the dispute shall be settled by binding arbitration pursuant to 
Section 12.13 herein. The arbitrators shall be independent persons with 
expertise in patent law and medicinal chemistry. Each party shall present a 
written statement of its position to the arbitrators and the other party, and 
the arbitrators shall evaluate such statements, and such other evidence as 
the arbitrators deem appropriate, and shall select the statement of one of 
the parties as their position; provided, however, Bayer shall be responsible 
for presenting evidence establishing that such product meets the criteria set 
forth in Section 1.13 above. In the event that the arbitrators determine that 
the Excluded Product that is the subject of the arbitration is an Agreement 
Product, then Bayer shall pay to Pharmacopeia liquidated damages  [ * * * ]  
due Pharmacopeia pursuant to Section 4.2.1 which were not timely paid to 
Pharmacopeia (without any obligation to pay interest from the dates such 
milestone payments originally should have been made), in addition to any 
other payments due under the Agreement.

[ * * *  Confidential Treatment Requested. ]


                                     -18-
<PAGE>


                                    ARTICLE 5
                           PAYMENTS; BOOKS AND RECORDS


    5.1    ROYALTY REPORTS AND PAYMENTS. After the first commercial sale of 
an Agreement Product on which royalties are payable by Bayer hereunder, Bayer 
shall make quarterly written reports to Pharmacopeia within ninety (90) days 
after the end of each calendar quarter, stating in each such report, 
separately for Bayer and each of its Affiliates and Sublicensees, the number, 
description, and aggregate Net Sales, by country, of each Agreement Product 
sold during the calendar quarter upon which a royalty is payable under 
Section 4.3 above. Subject to any reductions permitted pursuant to the 
express terms of this Agreement, concurrently with the making of such 
reports, Bayer shall pay to Pharmacopeia royalties at the rates specified in 
Section 4.3.

    5.2    PAYMENT METHOD. All payments due under this Agreement shall be 
made by bank wire transfer in immediately available funds to an account 
designated by Pharmacopeia. All payments hereunder shall be made in U.S. 
dollars. Any payments that are not paid on the date such payments are due 
under this Agreement shall bear interest to the extent permitted by 
applicable law at the prime rate as reported by the Chase Manhattan Bank, New 
York, New York, on the date such payment is due, calculated on the number of 
days such payment is delinquent.

    5.3    PLACE OF ROYALTY PAYMENT AND CURRENCY CONVERSIONS. If any currency 
conversion shall be required in connection with the calculation of royalties 
hereunder, such conversion shall be made using the selling exchange rate for 
conversion of the foreign currency into U.S. Dollars, quoted for current 
transactions reported in THE WALL STREET JOURNAL for the last business day of 
the calendar quarter to which such payment pertains. If at any time legal 
restrictions prevent the prompt remittance of any royalties owed on Net Sales 
in any jurisdiction, Bayer may make such payments by depositing the amount 
thereof in local currency in a bank account or other depository in such 
country in the name of Pharmacopeia. Bayer shall promptly notify Pharmacopeia 
of the circumstances leading to such deposit and, at Pharmacopeia's request, 
cooperate with Pharmacopeia to repatriate such amounts.

    5.4    RECORDS; INSPECTION. Bayer and its Affiliates and Sublicensees 
shall keep complete, true and accurate books of account and records for the 
purpose of determining the royalty amounts payable under this Agreement. Such 
books and records shall be kept at the principal place of business of such 
party, as the case may be, for at least three (3) years following the end of 
the calendar quarter to which they pertain. Such records will be open for 
inspection during such three (3) year period by a public accounting firm to 
whom Bayer has no reasonable objection, solely for the purpose of verifying 
royalty statements hereunder. Such inspections may be made no more than once 
each calendar year, at reasonable times and on reasonable notice. Inspections 
conducted under this Section 5.4 shall be at the expense of Pharmacopeia, 
unless a variation or error producing an increase exceeding five

                                  -19-

<PAGE>

percent (5)% of the amount stated for any period covered by the inspection is 
established in the course of any such inspection, whereupon all costs 
relating to the inspection for such period and any unpaid amounts that are 
discovered will be paid promptly by Bayer together with interest thereon from 
the date such payments were due at the prime rate as reported by the Chase 
Manhattan Bank, New York, New York. Pharmacopeia agrees to hold in strict 
confidence all information concerning royalty payments and reports, and all 
information learned in the course of any audit or inspection, except to the 
extent necessary for Pharmacopeia to reveal such information in order to 
enforce its rights under this Agreement or if disclosure is required by law. 
The public accounting firm employees shall sign customary confidentiality 
agreement as a condition precedent to their inspection and shall report to 
Pharmacopeia only that information which would be contained in a properly 
prepared royalty report by Bayer.

    5.5    TAX MATTERS.

           5.5.1  WITHHOLDING TAXES. All royalty amounts required to be paid 
to Pharmacopeia pursuant to this Agreement shall be paid with deduction for 
withholding for or on account of any taxes (other than taxes imposed on or 
measured by net income) or similar governmental charge imposed by a 
jurisdiction other than the United States ("Withholding Taxes") to the extent 
Pharmacopeia and/or its Affiliates or their successors has the lawful rights 
to utilize the Withholding Taxes paid by Bayer as a credit against 
Pharmacopeia's and/or its Affiliates' regular U.S. tax liability. Bayer shall 
provide Pharmacopeia a certificate evidencing payment of any Withholding Taxes 
hereunder.

           5.5.2  SALES TAXES. Any sales taxes, use taxes, transfer taxes or 
similar governmental charges required to be paid in connection with the 
transfer of the Bayer Random Libraries shall be the sole responsibility of 
Bayer. In the event that Pharmacopeia is required to pay any such amounts, 
Bayer shall promptly remit payment to Pharmacopeia of such amounts.


                                 ARTICLE 6
                             COMMERCIALIZATION


    6.1    DUE DILIGENCE. The selection of Active Compounds, Derivative 
Compounds and Agreement Products for development and commercialization shall 
be in the sole discretion of Bayer. Bayer shall, at Bayer's expense, be 
responsible for conducting all development of Agreement Compounds and 
Agreement Products, and all commercialization of Agreement Products. Bayer 
shall use its reasonable efforts to develop and commercialize Agreement 
Products as expeditiously as practicable and take such other actions as is 
necessary to obtain government approvals to market each Agreement Product in 
the Major Countries and other significant markets

                                      -20-



<PAGE>

throughout the world, and thereafter to promote each Agreement Product and 
meet the market demand therefor in such markets.

    6.2  LICENSE BACK.

         6.2.1  LACK OF DILIGENCE.  If, following the initial Exclusivity 
Period of the Bayer Random Library containing the Active Compound from which 
a particular Agreement Product is developed, Bayer fails to use diligent 
efforts pursuant to Section 6.1 of this Agreement to actively develop and 
commercialize such Agreement Product, or does not cure any such breach 
noticed by Pharmacopeia pursuant to Section 11.2 herein within the time 
permitted thereunder, or determines and provides Pharmacopeia notice that it 
will not commercialize such Agreement Product subject to this Agreement and 
so notifies Pharmacopeia, thereafter Bayer's rights with respect to the 
Active Compound from which such Agreement Product was developed shall 
terminate worldwide, subject to the following terms and conditions:

                (a)  Bayer may exercise due diligence itself or through 
Sublicensees. In the event that Bayer ceases its own diligent development 
and/or commercialization of an Agreement Compound, and within six (6) months 
of such cessation enters into an agreement with a Sublicensee providing that 
such Sublicensee shall diligently conduct such activities pursuant to Section 
6.1 above, then such cessation shall not terminate Bayer's rights with 
respect to the Active Compound from which such Agreement Compound was 
developed;

                (b)  if Bayer has identified at least one Lead Compound with 
activity against a particular molecular target and paid to Pharmacopeia the 
applicable milestone, then the subsequent diligent development and 
commercialization of one Agreement Product with activity against such 
molecular target, shall satisfy Bayer's diligence obligations with respect to 
all Active Compounds with activity against the same molecular target;

                (c)  even if Bayer has failed to satisfy its diligence 
requirements under Section 6.1, Bayer may retain exclusive rights to a 
particular Active Compound after such time by paying to Pharmacopeia an 
annual fee of  [ * * * ]  per such Active Compound, which amount shall be 
paid on each anniversary of the Effective Date; and

                (d)  even if Bayer has failed to satisfy its diligence 
requirements under Section 6.1, Bayer may retain exclusive rights to all 
Active Compounds with activity against a particular molecular target by 
paying to Pharmacopeia an annual fee of  [ * * * ]  which amount shall be 
paid on each anniversary of the Effective Date.

[ * * *  Confidential Treatment Requested. ]


                                     -21-

<PAGE>

In the event that Bayer's rights terminate with respect to any Active 
Compound under this Section 6.2, Bayer shall grant and hereby grants to 
Pharmacopeia or its designee, a non-exclusive, worldwide, royalty-free, 
irrevocable license under the Bayer Technology, including the right to grant 
and authorize sublicenses, to make, have made, use, have used, import, have 
imported, offer for sale, have sold and sell such Active Compound; provided, 
however, if any such Active Compound ever was a Lead Compound, then the 
foregoing license shall be royalty-bearing rather than royalty-free, and 
Pharmacopeia shall pay to Bayer a royalty negotiated in good faith by the 
parties which shall reflect the stage of commercial development and 
commercial value of such Active Compound. In the event Pharmacopeia wishes to 
acquire an exclusive license under the Bayer Technology with respect to such 
Active Compound, it may provide Bayer notice thereof, and the parties shall 
promptly negotiate in good faith an exclusive, worldwide, royalty-bearing 
license, with the right to grant and authorize sublicenses, to make, have 
made, use, have used, import, have imported, offer for sale, have sold and 
sell such Active Compound and products based thereon.

         6.2.2  ROYALTIES TO BAYER.  In the event that Bayer agrees to 
allow Pharmacopeia to acquire rights to any Derivative Compound or Agreement 
Product, then the parties shall negotiate in good faith terms under which 
Pharmacopeia will receive an exclusive, worldwide license, with the right to 
grant sublicenses, to make, have made, use, import, have imported, offer for 
sale, sell or otherwise exploit such Derivative Compound or Agreement Product.

    6.3  REGULATORY FILINGS.  If Pharmacopeia acquires rights from Bayer 
with respect to any Active Compound, Derivative Compound or Agreement Product 
pursuant to Sections 6.2.1 or 6.2.2 above, upon the request of Pharmacopeia, 
Bayer may, in exchange for agreed consideration, provide Pharmacopeia with 
access to and the right to use all regulatory filings made by Bayer or its 
Affiliates or Sublicensees to the extent possible with respect to such Active 
Compound, Derivative Compound or Agreement Product, together with the 
underlying pre-clinical and clinical data relating thereto, and agreed 
government permits and health registrations and other rights pertaining 
thereto.


                                   ARTICLE 7
                             INTELLECTUAL PROPERTY

    7.1  OWNERSHIP OF INVENTIONS.  Title to all inventions and other 
intellectual property made by employees of Bayer or its Affiliates, but not 
Pharmacopeia based on Bayer Random Libraries ("Bayer Inventions") shall be 
deemed owned by Bayer. Title to all inventions and other intellectual 
property made solely by employees of Pharmacopeia, but not Bayer or its 
Affiliates based on Bayer Random Libraries ("Pharmacopeia Inventions") shall 
be deemed owned by Pharmacopeia. Title to all inventions and other 
intellectual property made jointly by employees of Bayer or its 


                                     -22-

<PAGE>

Affiliates and Pharmacopeia based on Bayer Random Libraries ("Joint 
Inventions") shall be deemed jointly owned by Pharmacopeia and Bayer. 
Inventorship of inventions and other intellectual property rights conceived 
and/or reduced to practice pursuant to this Agreement, and rights of 
ownership with respect thereto, shall be discussed by patent counsel of Bayer 
and Pharmacopeia prior to the filing of each patent application subject to 
this Agreement. Inventorship shall be determined in accordance with the 
patent laws of the country or countries in which such inventions or other 
intellectual property were made. In the event that the parties disagree as to 
inventorship and/or the applicable law with respect to any invention or patent
application, such matter shall be subject to resolution pursuant to Section
12.13.

    7.2  PATENT PROSECUTION.

         7.2.1  RESPONSIBILITIES.

                (a)  PHARMACOPEIA INVENTIONS.  Pharmacopeia shall be 
responsible for preparing, filing, prosecuting and maintaining in the Core 
Countries and such other countries it deems appropriate, patent applications 
and patents relating to all Pharmacopeia Inventions included within the 
Licensed Technology and conducting any interferences, re-examinations, 
reissues or oppositions relating to such Licensed Technology. As used in this 
Agreement, "Core Countries" shall mean the United States, Canada, Europe 
(members of the European Patent Convention via European Patent Office 
applications) and Japan.

                (b)  JOINT INVENTIONS.  Subject to Sections 7.2.3 and 
7.2.4, Bayer shall be responsible for preparing, filing, prosecuting and 
maintaining in the Core Countries and such additional countries designated by 
Bayer, patent applications and patents relating to all Joint Inventions 
included within the Licensed Technology and conducting any interferences, 
re-examinations, reissues or oppositions relating to such Licensed Technology.

                (c)  BAYER INVENTIONS.  Bayer shall be responsible for 
preparing, filing, prosecuting and maintaining worldwide in such countries it 
deems appropriate, patent applications and patents, and conducting any 
interferences, re-examinations, reissues, or oppositions or requests for 
patent term extension or governmental equivalents thereto relating to Bayer 
Inventions.

         7.2.2  FAILURE TO PROSECUTE

                (a)  Bayer may elect upon ninety (90) days prior notice 
to discontinue prosecution of any patent applications filed pursuant to 
Section 7.2.1 (b) above and/or not to file or conduct any further activities 
with respect to the patent applications or patents subject to such Section. 
In the event Bayer declines to file or having filed fails to further 
prosecute or maintain any patent applications or patents


                                     -23-

<PAGE>

subject to Section 7.2.1 (b) above, or conduct any interferences, 
re-examinations, reissues, or oppositions, at Pharmacopeia's request, Bayer 
shall assign to Pharmacopeia its entire interest in such patent applications 
and patents. In such event, Pharmacopeia shall have the right to prepare, 
file, prosecute and maintain such patent applications and patents in such 
countries worldwide it deems appropriate, and conduct any interferences, 
re-examinations, reissues or oppositions, at its sole expense. In such event, 
Bayer shall cooperate with Pharmacopeia, at Pharmacopeia's request and 
expense, to perfect and record such assignments, and defend and enforce such 
patent rights.

                (b)  Pharmacopeia may at its sole discretion discontinue 
any or all of its activities subject to Section 7.2.1(a) above. In the event
Pharmacopeia declines to file or having filed fails to further prosecute or 
maintain any patent applications or patents subject to Section 7.2.1(a) 
above, or conduct any interferences, re-examinations, reisssues, oppositions, 
at Bayer request, Pharmacopeia shall assign to Bayer its entire interest in 
such patent applications and patents. In such event, Bayer shall have the 
right to prepare, file, prosecute and maintain such patent applications and 
patents in such countries worldwide it deems appropriate, and conduct any 
interferences, re-examinations, reissues or oppositions, at its sole expense. 
In such event, Pharmacopeia shall cooperate with Bayer, at Bayer's request 
and expense, to perfect and record such assignments, and defend and enforce 
such patent rights.

         7.2.3  COOPERATION.  Each of Bayer and Pharmacopeia shall keep 
the other fully informed as to the status of patent matters described in this 
Article 7, including, without limitation, by providing the other the 
opportunity to fully review and comment as far in advance of filing dates as 
feasible on any documents which will be filed in any patent office, and 
providing the other copies of any documents that such party receives from 
such patent offices promptly after receipt, including notice of all 
interferences, reissues, re-examinations, oppositions or requests for patent 
term extensions. Bayer and Pharmacopeia shall each reasonably cooperate with 
and assist the other at its own expense in connection with such activities, 
at the others party's request. Patent counsel designated by each party will 
meet at least on a semi-annual basis, unless otherwise agreed in writing, 
during (i) the Exclusivity Period for each Bayer Random Library, and (ii) the 
pendency of any patent applications claiming Joint Inventions subject to this 
Section 7.2 to coordinate, discuss, review and implement patent filing and 
prosecution strategy.

         7.2.4 COSTS.  Responsibilities for costs incurred under this 
Article shall be allocated, as follows:

               (i)  Pharmacopeia shall pay all costs incurred pursuant
                    to Section 7.2.1 (a); and 


                                     -24-

<PAGE>

               (ii)  Bayer shall pay all costs incurred pursuant to Section 
                     7.2.1(b) and (c).

          7.2.5  COPIES. Bayer shall promptly provide to Pharmacopeia a copy 
of any patent applications filed by Bayer or its Affiliates or Sublicensees 
during the term of this Agreement with respect to any Agreement Compounds, 
except with respect to Excluded Products. Pharmacopeia shall promptly provide 
to Bayer a copy of any patent applications filed by Pharmacopeia or its 
Affiliates during the term of this Agreement with respect to any Agreement 
Compounds.

     7.3  ENFORCEMENT AND DEFENSE.

          7.3.1  ENFORCEMENT. Each party shall promptly notify the other of 
its knowledge of any potential infringement of the Licensed Technology by a 
third party. Unless Bayer's interest in such Licensed Technology has been 
assigned to Pharmacopeia pursuant to Section 7.2.2(a), Bayer has the right, 
but not the obligation, to take reasonable legal action necessary to protect 
the Licensed Technology described in Section 7.2.1(b) against infringements 
by third parties. If within six (6) months following receipt of such notice 
from Pharmacopeia, Bayer fails to take such Action to halt a commercially 
significant infringement, Pharmacopeia shall, in its sole discretion, have 
the right, at its expense, to take such action as it deems warranted in its 
own name or in the name of Bayer or jointly to cease any infringement with 
respect to the Licensed Technology subject to Section 7.2.1(b). Each party 
agrees to render such reasonable assistance as the prosecuting party may 
request.  [ * * * ]  Pharmacopeia shall have the right to enforce patents 
described in Section 7.2.1(a) in its sole discretion.

          7.3.2  INFRINGEMENT CLAIMS. If the manufacture, sale or use of any 
Agreement Product pursuant to this Agreement because of the practice of the 
Licensed Technology, the Excluded Technology or the Bayer Technology results 
in any claim, suit or proceeding alleging patent infringement against 
Pharmacopeia or Bayer (or its Affiliates or Sublicensees), such party shall 
promptly notify the other party hereto in writing setting forth the facts of 
such claim in reasonable detail. The party subject to such claim shall have 
the exclusive right and obligation to defend and control the defense of any 
such claim, suit or proceeding, at its own expense, using counsel of its own 
choice; provided, however, it shall not enter into any settlement which 
admits or concedes that any aspect of the Bayer Technology (in the case of 
Pharmacopeia), or the Licensed Technology or Excluded Technology (in the case 
of Bayer), is invalid or unenforceable without the prior written consent of 
such other party. The party subject to the claim shall keep the other party 
hereto reasonably informed of all material developments in connection with 
any such claim, suit or proceeding.

[ * * *  Confidential Treatment Requested. ]


                                     -25-
<PAGE>

                                    ARTICLE 8
                                 CONFIDENTIALITY

     8.1  CONFIDENTIAL INFORMATION. Except as expressly provided herein, the 
parties agree that, for the term of this Agreement and for  [ * * * ]  
thereafter, the receiving party shall not, except as expressly provided in 
this Article 8, disclose to any third party or use for any purpose any 
confidential information furnished to it by the disclosing party pursuant to 
this Agreement ("Confidential Information") except to the extent that it can 
be established by the receiving party by competent proof that such 
information:

          (a)  was already known to the receiving party, other than under an 
obligation of confidentiality, at the time of disclosure;

          (b)  was generally available to the public or otherwise part of the 
public domain at the time of its disclosure to the receiving party;

          (c)  became generally available to the public or otherwise part of 
the public domain after its disclosure and other than through any act or 
omission of the receiving party in breach of this Agreement;

          (d)  was independently developed by the receiving party as 
demonstrated by documented evidence prepared contemporaneously with such 
independent development; or 

          (e)  was disclosed to the receiving party other than under an 
obligation of confidentiality, by a third party who had no obligation to the 
disclosing party not to disclose such information to others.

     8.2  PERMITTED USE AND DISCLOSURES. Each party hereto may use or 
disclose Confidential Information disclosed to it by the other party to the 
extent such information is included in the Licensed Technology or Bayer 
Technology, as the case may be, and to the extent such use or disclosure is 
reasonably necessary and permitted in the exercise of the rights granted 
hereunder in filing or prosecuting patent applications, prosecuting or 
defending litigation, complying with applicable governmental regulations or 
court orders or otherwise submitting information to tax or other governmental 
authorities, conducting clinical trials, or making a permitted sublicense or 
otherwise exercising license rights expressly granted to the other party to 
it pursuant to the terms of this Agreement, provided that if a party is 
required to make any such disclosure of another party's Confidential 
Information, other than pursuant to a confidentiality agreement, it will give 
reasonable advance notice to the other party of such disclosure and, save to 
the extent inappropriate in the case of patent applications, will use 
reasonable efforts to secure confidential treatment of such Confidential 
Information in consultation with the other party prior to its disclosure

[ * * *  Confidential Treatment Requested. ]


                                     -26-
<PAGE>

(whether through protective orders or otherwise) and disclose only the 
minimum necessary to comply with such requirements.

     8.3  NONDISCLOSURE OF TERMS. Each of the parties hereto agrees not to 
disclose to any third party the terms of this Agreement without the prior 
written consent of the other party hereto, except to such party's attorneys, 
advisors, investors and others on a need to know basis under circumstances 
that reasonably ensure the confidentiality thereof, or to the extent required 
by law. Notwithstanding the foregoing, the parties shall agree upon a press 
release to announce the execution of this Agreement, together with a 
corresponding Q&A outline for use in responding to inquiries about the 
Agreement; thereafter, Pharmacopeia and Bayer may each disclose to third 
parties the information contained in such press release and Q&A without the 
need for further approval by the other. In addition, Pharmacopeia may make 
public statements regarding progress with respect to the development and 
commercialization of Agreement Products, including announcement of the 
achievement of milestones and fees therefor, following consultation with 
Bayer and with the written consent of Bayer. At least ten (10) business days 
before submission, Pharmacopeia shall provide Bayer an opportunity to review 
any copy of this Agreement which Pharmacopeia intends to file with the U.S. 
Securities and Exchange Commission or equivalent entity.

     8.4  PUBLICATION. Until the end of the Exclusivity Period of any 
particular Library Compound, any manuscript, abstract or presentation 
(including information to be presented verbally) by Pharmacopeia or Bayer or 
its Affiliates or Sublicensees describing Active Compounds or Derivative 
Compounds or Agreement Products based thereon shall be subject to the prior 
review of the other party at least ninety (90) days prior to submission. 
Further, to avoid loss of patent rights as a result of premature public 
disclosure of patentable information, the receiving party shall notify the 
disclosing party in writing within thirty (30) days after receipt of such a 
disclosure whether the receiving party desires to file a patent application 
on any invention disclosed in such scientific results. In the event that the 
receiving party desires to file such a patent application, the disclosing 
party shall withhold publication or disclosure of such scientific results 
until the earlier of (i) a patent application is filed thereon, or (ii) the 
parties determine after consultation that no patentable invention exists, or 
(iii) one hundred and eighty (180) days after receipt by the disclosing party 
of the receiving party's written notice of the receiving party's desire to 
file such patent application, or such other period as is reasonable for 
seeking patent protection. Further, if such scientific results contain the 
information of the receiving party that is subject to use and nondisclosure 
restrictions under this Article 8, the disclosing party agrees to remove such 
information from the proposed publication or disclosure. Following the filing 
of any patent application within the Licensed Technology or Bayer Technology, 
in the eighteen (18) month period prior to the publication of such a patent 
application neither party shall make any public disclosure regarding any 
invention claimed in such patent application without the prior written 
consent of the other party.


                                     -27-
<PAGE>

                               ARTICLE 9
                    REPRESENTATIONS AND WARRANTIES

    9.1  BAYER.  Bayer warrants and represents on its own behalf and on 
behalf of its Affiliates that: (i) it has the legal power, authority and 
right to enter into this Agreement, and to perform all its obligations 
hereunder, and (ii) this Agreement is a legal and valid obligation binding 
upon it and enforceable in accordance with its terms.

    9.2  PHARMACOPEIA.  Pharmacopeia represents and warrants that: (i) it has 
the legal right and power to extend the rights granted in this Agreement; 
(ii) this Agreement is a legal and valid obligation binding upon it and 
enforceable in accordance with its terms; (iii) has the full right to enter 
into this Agreement, and to perform all of its obligations hereunder; (iv) it 
has not previously granted, and during the term of this Agreement will not 
knowingly make any commitment or grant any rights which are inconsistent in 
any material way with the rights and licenses granted herein; (v) to the best 
of its knowledge as of the Effective Date, there are no existing or 
threatened actions, suits or claims pending against it with respect to the 
Licensed Technology; (vi) to the best of its knowledge as of the Effective 
Date, the Licensed Technology does not include intellectual property licensed 
from third parties that would require Bayer to pay to such third parties a 
royalty to make, have made, use and sell Agreement Products; (vii) to the 
best of its knowledge as of the Effective Date, the practice by Pharmacopeia 
of the Excluded Technology does not infringe the intellectual property rights 
of third parties; and (viii) during the term of this Agreement, Pharmacopeia 
will use reasonable efforts not to materially breach the Columbia License.

    9.3  DISCLAIMER.  EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN THIS 
AGREEMENT, PHARMACOPEIA AND BAYER AND THEIR RESPECTIVE AFFILIATES MAKE NO 
REPRESENTATIONS AND EXTEND NO WARRANTIES OR CONDITIONS OF ANY KIND, EITHER 
EXPRESS OR IMPLIED, WITH RESPECT TO THE LICENSED TECHNOLOGY, THE BAYER 
TECHNOLOGY, BAYER RANDOM LIBRARIES, THE LIBRARY COMPOUNDS, ACTIVE COMPOUNDS, 
DERIVATIVE COMPOUNDS, AGREEMENT COMPOUNDS OR AGREEMENT PRODUCTS, OR 
INFORMATION DISCLOSED PURSUANT TO ARTICLE 8 INCLUDING, BUT NOT LIMITED TO, 
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, VALIDITY OF 
ANY LICENSED TECHNOLOGY, EXCLUDED TECHNOLOGY, OR BAYER TECHNOLOGY, PATENTED 
OR UNPATENTED, OR NONINFRINGEMENT OF THE INTELLECTUAL PROPERTY RIGHTS OF 
THIRD PARTIES.


                                   -28-

<PAGE>

                                ARTICLE 10
                             INDEMNIFICATION

    10.1  BAYER.  Bayer agrees to indemnify, defend and hold Pharmacopeia, 
its Affiliates and their directors, officers, employees agents and their 
respective successors, heirs and assigns (the "Pharmacopeia Indemnitees") 
harmless from and against any losses, costs, claims, damages, liabilities or 
expense (including reasonable attorneys' and professional fees and other 
expenses of litigation) (collectively, "Liabilities") arising, directly or 
indirectly out of or in connection with third party claims, suits, actions, 
demands or judgements, including, without limitation, personal injury and 
product liability matters, suits, actions, or demands relating to (i) any 
Agreement Products developed, manufactured, used, sold or otherwise 
distributed by or on behalf of Bayer, its Affiliates, Sublicensees or other 
designees (including without limitation, product liability claims), (ii) the 
use of the Bayer Random Libraries provided to Bayer hereunder; or (iii) any 
material breach by Bayer of the representations and warranties made in this 
Agreement, except in each case, to the extent such Liabilities resulted from 
a material breach of this Agreement by Pharmacopeia or negligence or 
intentional misconduct on the part of Pharmacopeia.

    10.2  PHARMACOPEIA.  Pharmacopeia agrees to indemnify, defend and hold 
Bayer, its Affiliates and their respective directors, officers, employees, 
agents and their respective successors, heirs and assigns (the "Bayer 
Indemnitees") harmless from and against any losses, costs, claims, damages, 
liabilities or expense (including reasonable attorneys' and professional fees 
and other expenses of litigation) (collectively, "Liabilities") arising, 
directly or indirectly out of or in connection with third party claims, 
suits, actions, demands or judgments, including without limitation personal 
injury and product liability matters, suits, actions, demands relating to (i) 
any Agreement Products developed, manufactured, used, sold or otherwise 
distributed by or on behalf of Pharmacopeia, its Affiliates, Sublicensees or 
other designees pursuant to Section 6.2 herein (including, without 
limitation, product liability claims), (ii) any action of Pharmacopeia in the 
preparation of Bayer Random Libraries and the decoding of Library Compounds 
in connection with the performance of this Agreement; and (iii) any material 
breach by Pharmacopeia of the representations and warranties made in this 
Agreement, except in each case, to the extent such Liabilities resulted from 
a material breach of this Agreement by Bayer or negligence or intentional 
misconduct on the part of Bayer.

    10.3  PROCEDURE.  In the event that any Indemnitee intends to claim 
indemnification under this Article 10 it shall promptly notify the other 
party in writing of such alleged Liability. The indemnifying party shall have 
the right to control the defense thereof with counsel of its choice, so long 
as such counsel is reasonably acceptable to Indemnitee; provided, however, 
that any Indemnitee shall have the right to retain its own counsel at its own 
expense, for any reason, including if representation of any Indemnitee by the 
counsel retained by the indemnifying party would be inappro-


                                   -29-
<PAGE>

priate due to actual or potential differing interests between such 
Indemnitee and any other party reasonably represented by such counsel in such 
proceeding. The affected Indemnitees shall cooperate with the indemnifying 
party and its legal representatives in the investigation of any action, claim 
or liability covered by this Article 10. The Indemnitee shall not, except at 
its own cost, voluntarily make any payment or incur any expense with respect 
to any claim or suit without the prior written consent of the indemnifying 
party, which such party shall not be required to give.

                               ARTICLE 11
                          TERM AND TERMINATION

    11.1  TERM.  Except as set forth below, the term of this Agreement shall 
begin as of the Effective Date and continue in full force and effect, on a 
country-by-country, and Agreement Product-by-Agreement Product basis, unless 
terminated earlier as provided in this Article 11, until Bayer, its 
Affiliates and Sublicensees, (or if pursuant to Section 6.2, Pharmacopeia and 
its Affiliates or Sublicensees), have no remaining royalty payment 
obligations in a country, at which time the Agreement shall expire in its 
entirety in such country.

    11.2  TERMINATION FOR BREACH.  Either party to this Agreement may 
terminate this Agreement as to the other party hereto in the event such other 
party shall have materially breached or defaulted in the performance of any 
of its material obligations hereunder, and such default shall have continued 
for sixty (60) days after written notice thereof was provided to the 
breaching party by the nonbreaching party. Any termination shall become 
effective at the end of such sixty (60) day period unless the breaching party 
(or any other party on its behalf) has cured any such breach or default prior 
to the expiration of the sixty (60) days; provided, however, in the case of a 
failure to pay any amount due hereunder, such default may be the basis of 
termination fifteen (15) business days following the date that notice of such 
default was provided to the breaching party.

    11.3  TERMINATION FOR INSOLVENCY.  If voluntary or involuntary 
proceedings by or against a party are instituted in bankruptcy under any 
insolvency law, or a receiver or custodian is appointed for such party, or 
proceedings are instituted by or against such party for corporate 
reorganization, dissolution, liquidation, or winding-up of such party, which 
proceedings, if involuntary, shall not have been dismissed within sixty (60) 
days after the date of filing, or if such party makes an assignment for the 
benefit of creditors, or substantially all of the assets of such party are 
seized or attached and not released within sixty (60) days thereafter, the 
other party may immediately terminate this Agreement effective upon notice of 
such termination.

    11.4  TERMINATION DUE TO ACQUISITION.  During the Initial Term (as defined 
in the Collaboration Agreement), if any third party which is a competitor of 
Bayer shall 


                                     -30-

<PAGE>

purchase substantially all the assets of Pharmacopeia or if there is a change 
of control of Pharmacopeia, Bayer may terminate this Agreement effective 
ninety (90) days after written notice is received by Pharmacopeia, or its 
parent, successor, surviving or the new entity, as the case may be. As used 
herein, change of control shall mean the acquisition by a third party which 
is a competitor of Bayer of forty percent (40%) or more of the voting stock 
of Pharmacopeia.

    11.5  CONCURRENT TERMINATION WITH THE COLLABORATION AGREEMENT.  In the 
event of any termination of the Collaboration Agreement during the Initial 
Term, this Agreement shall terminate concurrently.

    11.6  EFFECT OF BREACH OR TERMINATION.

          11.6.1  ACCRUED RIGHTS AND OBLIGATIONS.  Termination of this 
Agreement for any reason shall not release any party hereto from any 
liability which, at the time of such termination, has already accrued to the 
other party or which is attributable to a period prior to such termination, 
nor preclude either party from pursuing any rights and remedies it may have 
hereunder or at law or in equity which accrued or are based upon any event 
occurring prior to such termination.

          11.6.2  RETURN OF MATERIALS.  Upon any termination of this 
Agreement, Bayer and Pharmacopeia shall promptly return to the other party 
all Confidential Information (including without limitation all Existing and 
Future Know-How and Bayer Technology, as the case may be) received from the 
other party (except one copy of which may be retained for archival purposes) 
and any remaining Library Compounds in Bayer's possession.

          11.6.3  POST-TERMINATION PRODUCT SALES.  In the event of the 
cancellation or termination of any license rights with respect to an 
Agreement Product prior to the expiration thereof or termination of this 
Agreement, inventory of an Agreement Product may be sold for up to six (6) 
months after date of termination, provided earned royalties are paid thereon.

          11.6.4  LICENSES.  The licenses granted Bayer herein shall 
terminate in the event of a termination by Pharmacopeia pursuant to Section 
11.2 or 11.3, and any licenses granted to Pharmacopeia under Section 6.2 
shall terminate in the event of a termination by Bayer under Section 11.2, 
11.3 or 11.4; provided, however, in the event of a termination by Bayer 
pursuant to Section 11.4, the licenses granted by Pharmacopeia shall remain 
in effect with respect to the Licensed Technology existing as of the 
effective date of such termination, subject to the terms and conditions of 
this Agreement. If more than one Agreement Product is being commercially 
developed or exploited by Bayer, its Affiliates or Sublicensees hereunder and 
a breach entitling Pharmacopeia to terminate this Agreement relates solely to 
a single Agreement 


                                     -31-

<PAGE>

Product, then Pharmacopeia shall be entitled to terminate this Agreement only 
with respect to the applicable Agreement Product.

    11.7  SURVIVAL.  Sections 2.12, 3.5, 3.6, 3.7, 5.1, 5.4, 5.5, 6.2, 6.3, 
7.1, 7.2 and Articles 8, 9, 10, 11 and 12 of this Agreement shall survive the 
expiration or termination of this Agreement for any reason.

                                  ARTICLE 12
                                 MISCELLANEOUS

    12.1  GOVERNING LAWS.  This Agreement and any dispute arising from the 
performance or breach hereof shall be governed by and construed and enforced 
in accordance with, the laws of the state of New York, without reference to 
conflicts of laws principles and excluding any application of the United 
Nations Convention on the International Sale of Goods.

    12.2  NO IMPLIED LICENSES.  Only the licenses granted pursuant to the 
express terms of this Agreement shall be of any legal force or effect. No 
other license rights shall be created by implication, estoppel or otherwise.

    12.3  WAIVER.  It is agreed that no waiver by any party hereto of any 
breach or default of any of the covenants or agreements herein set forth 
shall be deemed a waiver as to any subsequent and/or similar breach or 
default.

    12.4  ASSIGNMENT.  This Agreement shall not be assignable by either party 
to any third party hereto without the written consent of the other party 
hereto except in the case of Bayer to its designated Affiliate(s), provided 
however, that Bayer guarantees the performance of such Affiliate(s) in a 
manner reasonably acceptable to Pharmacopeia. Either party may assign this 
Agreement, without such consent, to an entity that acquires all or 
substantially all of the business or assets of such party to which this 
Agreement pertains, whether by merger, reorganization, acquisition, sale, or 
otherwise. This Agreement shall be binding upon and accrue to the benefit or 
any permitted assignee, and any such assignee shall agree to perform the 
obligations of the assignor.

    12.5  INDEPENDENT CONTRACTORS.  The relationship of the parties hereto is 
that of independent contractors. The parties hereto are not deemed to be 
agents, partners or joint ventures of the others for any purpose as a result 
of this Agreement or the transactions contemplated thereby.

    12.6  COMPLIANCE WITH LAWS.  In exercising their rights under this 
license, the parties shall fully comply in all material respects with the 
requirements of any and all applicable laws, regulations, rules and orders of 
any governmental body having


                                     -32-


<PAGE>

jurisdiction over the exercise of rights under this license including, 
without limitation, those applicable to the discovery, development, 
manufacture, distribution, import and export and sale of pharmaceutical 
products pursuant to this Agreement.

    12.7  PATENT MARKING.  Bayer agrees to mark and have its Affiliates and 
Sublicensees mark all Agreement Products sold pursuant to this Agreement in 
accordance with the applicable statute or regulations relating to patent 
marking in the country or countries of manufacture and sale thereof.

    12.8  NOTICES.  All notices, requests and other communications hereunder 
shall be in writing and shall be personally delivered or by registered or 
certified mail, return receipt requested, postage prepaid, in each case to 
the respective address specified below, or such other address as may be 
specified in writing to the other parties hereto and shall be deemed to have 
been given upon receipt:

    Pharmacopeia:    Pharmacopeia
                     101 College Road East
                     Princeton, New Jersey 08540
                     Attn:  Chief Executive Officer

    with a copy to:  Wilson Sonsini Goodrich & Rosati
                     650 Page Mill Road
                     Palo Alto, California 94304-1050
                     Attn:  Michael S. Rabson, Esq.

    Bayer:           Bayer Corporation
                     Pharmaceutical Division
                     400 Morgan Lane
                     West Haven, Connecticut 06516
                     Attn:  Office of the President

    with a copy to:  Bayer Corporation
                     Pharmaceutical Division
                     400 Morgan Lane
                     West Haven, Connecticut 06516
                     Attn:  Office of the General Counsel

    12.9  SEVERABILITY.  In the event that any provision of this Agreement 
becomes or is declared by a court of competent jurisdiction to be illegal, 
unenforceable or void, this Agreement shall continue in full force and effect 
to the fullest extent permitted by law without said provision, and the 
parties shall amend the Agreement to the extent feasible to lawfully include 
the substance of the excluded term to as fully as possible realize the intent 
of the parties and their commercial bargain.


                                     -33-

<PAGE>


    12.10 FORCE MAJEURE. Neither party shall lose any rights hereunder or be 
liable to the other party for damages or losses (except for payment 
obligations) on account of failure of performance by the defaulting party if 
the failure is occasioned by war, strike, fire, Act of God, earthquake, 
flood, lockout, embargo, governmental acts or orders or restrictions, failure 
of suppliers, or any other reason where failure to perform is beyond the 
reasonable control and not caused by the negligence, intentional conduct or 
misconduct of the nonperforming party, provided such party has exerted all 
reasonable efforts to avoid or remedy such force majeure; provided, however, 
that in no event shall a party be required to settle any labor dispute or 
disturbance.

    12.11 NO CONSEQUENTIAL DAMAGES. In no event shall any party to this 
Agreement have any liability to the other for any special, consequential or 
incidental damages arising under this Agreement under any theory of liability.

    12.12 COMPLETE AGREEMENT. This Agreement with its Exhibits, together with 
the Collaboration Agreement and the Stock Purchase Agreement executed by the 
parties of even date herewith, constitutes the entire agreement, both written 
and oral, between the parties with respect to the subject matter hereof, and 
all prior agreements respecting the subject matter hereof, either written or 
oral, expressed or implied, shall be abrogated, canceled, and are null and 
void and of no effect. There are no covenants, promises, agreements, 
warranties, representations, conditions or understandings, either oral or 
written, between the parties other than as set forth herein and therein. No 
amendment or change hereof or addition hereto shall be effective or binding 
on either of the parties hereto unless reduced to writing and executed by the 
respective duly authorized representatives of Pharmacopeia and Bayer.

    12.13 DISPUTE RESOLUTION.

          12.13.1 The parties recognize that disputes as to certain matters 
may from time to time arise during the term of this Agreement relating to 
either party's rights and/or obligations hereunder. The parties shall follow 
the procedures set forth in this paragraph to facilitate the resolution of 
disputes arising under this Agreement in an attempt to avoid the submission 
of disputes to arbitration pursuant to this Section 12.13.1 Any disputes 
among the members of the RSC, or other disputes between the parties, that 
cannot be resolved by good faith negotiation, shall be referred, by written 
notice from either party to the other, to the respective officers of the 
parties designated below (or their successors).


                  For Bayer:  President of the Pharmaceutical Division

                  For Pharmacopeia:  Chief Executive Officer


                                    -34-


<PAGE>


Such executive officers shall negotiate in good faith to achieve a resolution 
to the dispute referred to them within thirty (30) days after such notice is 
received.

          12.13.2 Any dispute or controversy arising out of or related to 
this Agreement which is not resolved pursuant to Section 12.13.1 within thirty 
(30) days shall be finally settled by binding arbitration, conducted in 
accordance with the Commercial Arbitration Rules of the American Arbitration 
Association by three arbitrators appointed in accordance with said rules (the 
"Arbitrators"). The arbitration shall be held in New York, New York. At least 
one of the Arbitrators shall be an independent expert with expertise in 
pharmaceutical product development generally, and if possible, in the 
specific discipline to which the dispute predominantly relates. The 
Arbitrators shall determine what discovery will be permitted, consistent with 
the goal of limiting the cost and time which the Parties must expend for 
discovery; provided the Arbitrators shall permit such discovery as they deem 
necessary to permit an equitable resolution of the dispute. Any written 
evidence originally in a language other than English shall be submitted in 
English translation accompanied by the original or a true copy thereof. The 
governing law provided for under Section 12.1 hereof shall be applied to all 
matters in dispute between the parties with respect to this Agreement.

          12.13.3 Each party shall bear its own costs and attorneys' and 
witness' fees. The costs of the administration of the arbitration, including 
arbitrator's fees and administrative fees and expenses, shall be shared 
equally by the parties. A disputed performance or suspended performances 
pending the resolution of the arbitration must be completed within thirty 
(30) days following the final decision of the Arbitrators or such other 
reasonable period as the Arbitrators determine in a written opinion. A 
decision (the "Decision") shall be rendered within one (1) year from the date 
the dispute is submitted to arbitration pursuant to this section. The 
arbitral proceedings and the Decision shall not be made public without the 
joint consent of the parties and each party shall maintain the 
confidentiality of such proceedings and Decision unless otherwise permitted 
by the other party. Any Decision which requires a monetary payment shall 
require such payment to be payable in United States Dollars, free of any tax 
or other deduction. The parties agree that the Decision shall be the sole, 
exclusive and binding remedy between them regarding any and all disputes, 
controversies, claims and counterclaims presented to the Arbitrators. Each 
party hereby expressly waives any and all rights such party may have with 
respect to a judicial review of the Decision in the courts of any country. 
Application may be made to any court having jurisdiction over the party (or 
its assets) against whom the Decision is rendered for a judicial validation, 
acceptance, and recognition of the Decision and an order of enforcement.

    12.14 CONSENTS NOT UNREASONABLY WITHHELD. Whenever a provision is made in 
this Agreement for either party to secure the consent or approval of the 
other, that consent or approval shall not unreasonably be withheld or 
delayed, and whenever in


                                   -35-


<PAGE>


this Agreement provision is made for one party to object or disapprove of a
matter, such objection or disapproval shall not unreasonably be exercised.

    12.15 FURTHER ACTIONS. Each party agrees to execute, acknowledge and 
deliver such further instruments, and to do all such other acts, as may be 
necessary or appropriate in order to carry out the purposes and intent of 
this Agreement.

    12.16 NO TRADEMARK RIGHTS. Except as otherwise provided herein, no right, 
express or implied, is granted by the Agreement to use in any manner the name 
"Pharmacopeia" or "Bayer", or any other trade name or trademark of the other 
party or its Affiliates, if any, in connection with the performance of this 
Agreement.

    12.17 PERFORMANCE OF AFFILIATES AND SUBLICENSEES. Bayer shall be 
responsible for the compliance of its Affiliates and Sublicensees with the 
terms and conditions of this Agreement, and for any liabilities arising from 
the practice by such entities of the rights granted herein.

    12.18 HEADINGS. The captions to the several Sections hereof are not a 
part of this Agreement, but are included merely for convenience of reference 
only and shall not affect its meaning or interpretation.

    12.19 COUNTERPARTS. This Agreement may be executed in counterparts, each 
of which shall be deemed to be an original and all of which together shall be 
deemed to be one and the same agreement.

    IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be 
duly executed by their authorized representatives and delivered in duplicate 
originals.



BAYER CORPORATION                  PHARMACOPEIA, INC.                         
                                                                              
By:   /s/ Gerd D. Muller           By:  /s/ Joseph A. Mollica                 
   ------------------------------      ---------------------------------------
                                                                              
Name:  Gerd D. Muller              Name:   Joseph A. Mollica                  
     ----------------------------       --------------------------------------
                                   
Title: Executive Vice President    Title: Chairman and Chief Executive Officer
      ---------------------------        -------------------------------------



                                  -36-


<PAGE>

                                  EXHIBIT A

    1.  Pharmacopeia will provide to Bayer Random Libraries containing a 
minimum of  [ * * * ]  different compounds per year, in  [ * * * ]  libraries 
arrayed in 96-well microtiter plates suitable for high throughput screening. 
No Random Library will contain less than  [ * * * ]  members. The number of 
compounds in each well of the sets of microtiter plates produced for a given 
assay will be determined by Bayer but will be within a range of  [ * * * ]  
compounds per well. The type of plate and format for control wells will also 
be determined by Bayer subject to compatibility with Pharmacopeia's 
production processes.

    2.  Once the format and number of compounds per well is agreed for each 
assay, Pharmacopeia will then provide for each assay that number of plates 
required to contain  [ * * * ]  compounds as are contained in each library, 
E.G. for each assay  [ * * * ]  randomly selected compounds would be provided 
for a library of  [ * * * ]  members  [ * * * ]  As an example, a         
member library arrayed at  [ * * * ]  compounds per well in  [ * * * ]  wells 
at  [ * * * ]  redundancy would require  [ * * * ]  plates for one assay. The 
total number of plates will not exceed  [ * * * ]  per Random Library. 
Pharmacopeia will  [ * * * ]  Pharmacopeia will then decode the chemical 
structure from single active compounds within 1 month of notification of a 
request for decoding by Bayer. Pharmacopeia will perform up to  [ * * * ]  
and decodes per library at a rate of up to  [ * * * ]  and  [ * * * ]  
decodes per month.

    3.  Plates will be provided  [ * * * ]  consistent with Bayer's ability 
to screen compounds, but in no event  [ * * * ]  more than a total (for all  
[ * * * ]  of  [ * * * ]  plates per month. After the first year of the 
agreement, this rate of plate supply may be increased by  [ * * * ]  plates 
per month upon  [ * * * ]  prior written request by Bayer. Pharmacopeia 
recommends that plates be delivered to each assay in a just-in-time fashion 
to minimize the possibility of compound decomposition upon storage.

    4.  For up to  [ * * * ]  from delivery of a set of plates, Pharmacopeia 
will store the corresponding "master" plates containing the same compounds 
but attached to solid support.

    5.  Pharmacopeia shall not be responsible for replacing plates which are 
rendered unusable due to Bayer's failure to promptly screen, or store 
libraries under conditions recommended by Pharmacopeia at the time of 
delivery; provided, Bayer may request Pharmacopeia to replace such plates on 
the terms and conditions set forth herein.

[ * * *  Confidential Treatment Requested. ]


<PAGE>

                                  EXHIBIT B

                              BAYER AFFILIATES



                                  [ * * * ]



[ * * *  Confidential Treatment Requested. ]


Source: OneCLE Business Contracts.