PHARMACOPEIA INC
10-K405/A, 1996-05-09
COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH
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                          SECURITIES AND EXCHANGE COMMISSION
                                Washington, D.C. 20549

                                     FORM 10-K/A

                                      (Mark One)

         /X/  Annual Report Pursuant to Section 13 or 15(d) of the Securities
              Exchange Act of 1934

                     FOR THE FISCAL YEAR ENDED DECEMBER 31, 1995

         / /  Transition report pursuant to Section 13 or 15(d) of the
              Securities Exchange Act of 1934
                     For the Period From _________ to __________.

                           Commission File Number:  0-27188

                                  PHARMACOPEIA, INC.
                (Exact name of Registrant as specified in its charter)

            DELAWARE                                      33-0557266
  -------------------------------        ---------------------------------------
  (State or other jurisdiction of        (I.R.S. employer identification number)
   incorporation or organization)

                      101 COLLEGE ROAD EAST, PRINCETON, NJ 08540
                (Address of principal executive offices and zip code)

                                    (609) 452-3600
                 (Registrant's telephone number, including area code)

          Securities registered pursuant to Section 12(b) of the Act:  None
                                                                       ----
            Securities registered pursuant to Section 12(g) of the Act:
                            Common Stock $.0001 Par Value
                            -----------------------------

    Indicate by check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter periods as the
Registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.

                                YES   X      NO
                                    -----        -----

    Indicate by check mark if disclosure of delinquent filers pursuant to
Item 405 of Regulation S-K is not contained herein, and will not be contained,
to the best of Registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K/A or any
amendment to this Form 10-K/A.  /X/

    As of February 29, 1996, the approximate aggregate market value of voting
stock held by nonaffiliates of the Registrant was $168,129,047.  4,288,746
shares of Common Stock held by  officers, directors, and holders of 5% or more
of the outstanding Common Stock have been excluded in that such persons may be
deemed to be affiliates.  This determination of affiliate status is not
necessarily a conclusive determination for other purposes.

    As of February 29, 1996, the number of outstanding shares of the
Registrant's Common Stock was 10,603,452.


                         DOCUMENTS INCORPORATED BY REFERENCE

    Certain information required by Part III of Form 10-K/A is incorporated by
reference from the Registrant's Proxy Statement for the Annual Stockholders
Meeting to be held June 3, 1996 (the "Proxy Statement"), which will be filed
with the Securities and Exchange Commission within 120 days after the close of
the Registrant's fiscal year ended December 31, 1995.

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                                  PHARMACOPEIA, INC.

                                    1995 FORM 10-K

                                  TABLE OF CONTENTS
                                                                            Page
                                                                            ----
PART IV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS
         ON FORM 8-K  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

SIGNATURES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27


                                         -2-

<PAGE>

                                       PART IV

    This amendment to Form 10-K on Form 10-K/A is submitted in response to the
Securities and Exchange  Commision's response to the Registrant's request for
confidentiality treatment filed on March 25, 1996.  The only Item revised as a
result of this amendment is Item 14.

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K

  Exhibits
  --------
    3.1*      RESTATED CERTIFICATE OF INCORPORATION OF THE REGISTRANT.
    3.3*      BYLAWS OF THE REGISTRANT.
    4.3*      STOCKHOLDERS RIGHTS AGREEMENT, DATED FEBRUARY 15, 1995.
    10.1*     SERIES A AND SERIES B PREFERRED STOCK PURCHASE AGREEMENT, DATED
              JULY 21, 1993.
    10.2*     SERIES B PREFERRED STOCK PURCHASE AGREEMENT, DATED MARCH 11, 1994.
    10.3*     SERIES C PREFERRED STOCK PURCHASE AGREEMENT, DATED DECEMBER 22,
              1994.
    10.4*     SERIES D PREFERRED STOCK PURCHASE AGREEMENT, DATED FEBRUARY 15,
              1995.
    10.5      AMENDED 1994 INCENTIVE STOCK PLAN.
    10.6*     1995 EMPLOYEE STOCK PURCHASE PLAN.
    10.7*     1995 DIRECTOR OPTION PLAN.
    10.8+*    LIBRARY COLLECTION AGREEMENT, DATED AS OF OCTOBER 1, 1995,
              BETWEEN PHARMACOPEIA AND SANDOZ PHARMA LTD.
    10.9+*    RESEARCH, LICENSE, AND ROYALTY AGREEMENT, DATED AS OF FEBRUARY
              15, 1995, BETWEEN PHARMACOPEIA AND BERLEX LABORATORIES, INC.
    10.10+*   LICENSE AGREEMENT, DATED AS OF OCTOBER 6, 1995, AMONG
              PHARMACOPEIA, THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY .
              OF NEW YORK AND COLD SPRING HARBOR LABORATORY.
    10.11+*   COLLABORATION AGREEMENT, DATED AS OF DECEMBER 22, 1994, BETWEEN
              PHARMACOPEIA AND SCHERING CORPORATION AND SCHERING-PLOUGH, LTD.
    10.12+*   RANDOM LIBRARY AGREEMENT, DATED AS OF DECEMBER 22, 1994, BETWEEN
              PHARMACOPEIA AND SCHERING CORPORATION AND SCHERING-PLOUGH, LTD.
    10.13*    LEASE AGREEMENT BETWEEN PHARMACOPEIA AND EASTPARK AT 8A.
    10.13(A)  AMENDMENT DATED JANUARY 22, 1996 TO LEASE AGREEMENT BETWEEN
              PHARMACOPEIA AND EASTPARK AT 8A
    10.14*    SUBLEASE, DATED AS OF DECEMBER 7, 1994, BETWEEN PHARMACOPEIA AND
              ENICHEM AMERICAS, INC.
    10.15*    LEASE, DATED AS OF MAY 2, 1994, BETWEEN PHARMACOPEIA AND COLLEGE
              ROAD ASSOCIATES LIMITED, AS AMENDED.
    10.15(A)  LEASE, DATED AS OF DECEMBER 1, 1995, BETWEEN PHARMACOPEIA AND
              COLLEGE ROAD ASSOCIATES LIMITED, AS AMENDED.
    10.16*    SUBLEASE AGREEMENT, DATED AS OF OCTOBER 29, 1993, BETWEEN
              PHARMACOPEIA AND CYTOGEN CORPORATION.
    10.17*    EMPLOYMENT AGREEMENT, DATED OCTOBER 4, 1994, BETWEEN THE COMPANY
                AND LEWIS J. SHUSTER.
    10.18*    EMPLOYMENT AGREEMENT, DATED JANUARY 18, 1994, BETWEEN THE COMPANY
                AND JOSEPH A. MOLLICA, PH.D.
    10.19*    EMPLOYMENT AGREEMENT, DATED MAY 18, 1993, BETWEEN THE COMPANY AND
                JOHN C. CHABALA, PH.D.
    10.20*    EMPLOYMENT AGREEMENT, DATED JUNE 3, 1993, BETWEEN THE COMPANY AND
                JOHN J. BALDWIN, PH.D.
    10.21*    EMPLOYMENT AGREEMENT, DATED DECEMBER 2, 1993, BETWEEN THE COMPANY
                AND NOLAN H. SIGAL, M.D., PH.D.
    10.22*    CONSULTING AGREEMENT, DATED APRIL 30, 1993, BETWEEN THE COMPANY
              AND W. CLARK STILL, PH.D.
    10.23*    WARRANT TO PURCHASE COMMON STOCK ISSUED TO COLUMBIA UNIVERSITY.
    10.24*    WARRANT TO PURCHASE COMMON STOCK ISSUED TO COLD SPRING HARBOR
              LABORATORY.
    10.25++   COLLABORATION AGREEMENT EFFECTIVE AS OF DECEMBER 31, 1995 BETWEEN
                PHARMACOPEIA AND BAYER
    10.26++   RANDOM LIBRARY AGREEMENT EFFECTIVE AS OF DECEMBER 31, 1995
              BETWEEN PHARMACOPEIA AND BAYER
    10.29     EMPLOYMENT AGREEMENT, DATED JANUARY 24, 1996, BETWEEN THE COMPANY
                AND NANCY M. GRAY, PH.D.
    11.1*     STATEMENT RE COMPUTATION OF PER SHARE EARNINGS.
    23.1*     CONSENT OF ERNST & YOUNG LLP.
    24.1*     POWERS OF ATTORNEY.

- - -------------------
*  PREVIOUSLY FILED ON FORM S-1 AND FORM 10-K.
+  CONFIDENTIAL TREATMENT GRANTED.
++ REVISED EXHIBITS IN RESPONSE TO THE SEC'S COMMENTS TO CONFIDENTIAL TREATMENT
   REQUEST.


                                         -3-

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                                      SIGNATURES

    Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.

                                       PHARMACOPEIA, INC.


                                       By:  /s/ LEWIS J. SHUSTER
                                                ----------------
                                                Lewis J. Shuster
                                                Chief Financial Officer
                                                (Principal Accounting Officer)

                                       Date:  May 8, 1996

    Pursuant to the requirements of the Securities Exchange Act of 1934, this
Form 10-K/A has been signed below by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated:

Signature                         Title                              Date
- - ---------                         -----                              ----

             *
- - --------------------------
(Joseph A. Mollica, Ph.D.)   Chairman of the  Board             May 8, 1996
                             and Chief  Executive Officer
                             (Principal Executive Officer)

   /s/ LEWIS J. SHUSTER
- - --------------------------
    (Lewis J. Shuster)       Chief Financial Officer            May 8, 1996
                             (Principal Financial and
                             Accounting Officer)
             *
- - --------------------------
 (John C. Chabala, Ph.D.)    Director                           May 8, 1996

             *
- - --------------------------
    (Lawrence A. Bock)       Director                           May 8, 1996

             *
- - --------------------------
     (Brook E. Byers)        Director                           May 8, 1996

             *
- - --------------------------
    (Samuel D. Colella)      Director                           May 8, 1996

             *
- - --------------------------
      (Eileen M. More)       Director                           May 8, 1996

             *
- - --------------------------
     (Gary E. Costley)       Director                           May 8, 1996

             *
- - --------------------------
  (W. Clark Still, Ph.D.)    Director                           May 8, 1996

  /s/ LEWIS J. SHUSTER
- - --------------------------
     (Lewis J. Shuster)      Attorney in Fact                   May 8, 1996


- - --------------------
* By Lewis J. Shuster, Attorney in Fact.


                                         -4-

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                                  INDEX TO EXHIBITS

      Exhibit                                               Sequentially
      Number              Exhibit Name                     Numbered Page
    --------- -------------------------------------------  -------------
    10.25 *   Collaboration Agreement effective as of
              December 31, 1995 between Pharmacopeia
              and Bayer.
    10.26 *   Random Library Agreement effective as of
              December 31, 1995 between Pharmacopeia
              and Bayer.


- - ----------------------
* Amended exhibits filed in response to the SEC's comments to confidential
  treatment request.


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                             COLLABORATION AGREEMENT

     This COLLABORATION 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 and screening of encoded compound libraries. Pharmacopeia believes
that its technology, by rapidly producing diverse and targeted compound
libraries will accelerate the drug discovery process and increase productivity
of drug discovery programs.

     B.   Bayer and Pharmacopeia desire to collaborate to design, synthesize and
screen compound libraries to identify Lead Compounds and potentially Development
Candidates (as defined herein) based on Bayer proprietary compound(s) which have
activity in the Designated Field.

     C.   On even date herewith, Bayer and Pharmacopeia have entered into a
Random Library Agreement pursuant to which Pharmacopeia will deliver to Bayer
certain Random Libraries for screening.

     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 as set forth herein.

     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 I
                                   DEFINITIONS

     1.1  "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 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

<PAGE>

controlling Pharmacopeia or Bayer at the maximum control or ownership right 
permitted in a country where such company exists.

     1.2  "AGREEMENT COMPOUNDS" shall mean Designated Compounds, Other 
Compounds and Derivative Compounds. Agreement Compounds shall not include 
Excluded Products.

     1.3  "AGREEMENT PRODUCTS" shall mean any product, including bulk active 
ingredients, containing an Agreement Compound. Agreement Products shall not 
include Excluded Products.

     1.4  "BAYER TECHNOLOGY" shall mean any patent application filed after 
Bayer's notice to Pharmacopeia pursuant to Section 2.1(a) below and before 
the Cutoff Date (or a division, continuation or continuation-in-part of any 
such patent application) or any patent issued on any of the preceding, 
including reissues or re-examinations, which is owned, 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.

     1.5  "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.

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

     1.7  "CUTOFF DATE" means the    [ * * *]    anniversary of the end of 
the Research Program.

     1.8  "DERIVATIVE COMPOUND" shall mean any compound that demonstrates 
activity in the Designated Field, or outside the Designated Field, as the 
case may be, which is derived by Pharmacopeia, or Bayer or its Affiliates or 
Sublicensees, or by a third party under authority from Bayer from a Library 
Compound. As used herein, a compound shall be deemed to have been "derived 
from" a Library Compound if it is a chemical modification made to a Library 
Compound which: (i) results from a chemical synthesis program based on a 
Library Compound, (ii) is based on structure-activity data relating to 
Library Compounds (with or without activity in the Designated Field), or 
(iii) is conceived and actually or constructively reduced to practice by 
Pharmacopeia, or Bayer or its Affiliates or Sublicensees, or by another third 
party under authority from Bayer in connection with the activities described 
in (i) or (ii) above. 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 a compound with activity 
in the Designated Field which meets the criteria above shall be a

[ * * *  Confidential Treatment Requested. ]

                                       -2-

<PAGE>

Derivative Compound, even if such compound also has biological activity 
outside the Designated Field. It is further understood that Derivative 
Compounds shall not include compounds "derived from" Excluded Products.

     1.9  "DESIGNATED COMPOUND" shall mean  any compound which demonstrates 
activity in the Designated Field in accordance with the criteria established 
by the parties pursuant to Section 2.1(d) in  a Library screened by 
Pharmacopeia during the term of and in the course of performing the Research 
Program. It is understood that Designated Compounds shall include compound(s) 
which also have biological activity outside the Designated Field, provided 
they have the level of activity with respect to the Designated Target as 
established by the parties pursuant to Section 2.1(d).

     1.10  "DESIGNATED FIELD" shall mean the therapeutic or prophylactic 
treatment or prevention of diseases and conditions in humans and animals, or 
a diagnostic use, through the use of a compound that has activity with 
respect to a Designated Target, even if such compound also has biological 
activity outside the Designated Target.

     1.11  "DESIGNATED TARGET" shall mean the molecular target which the 
parties agree is the subject of the Research Program subject to Section 2.1 
below.

     1.12  "DEVELOPMENT CANDIDATE" shall have the meaning set forth in 
Section 6.2.5.

     1.13  "EXCLUDED PRODUCT" shall mean any product for use in the 
Designated Field which contains:

           (i)  a proprietary chemical compound which Bayer or its Affiliates 
has developed independently of the intellectual property developed through 
the activities set forth in subsections 1.8(i) - (iii), which prior to the 
Effective Date, Bayer or a Bayer Affiliate has synthesized and either tested 
or has expressed an intention to test for activity in the Designated Field, 
in each case, as shown by contemporaneous documentation, provided any such 
compound demonstrates activity in the Designated Field, subject to reasonable 
verification;

           (ii)  any Derivative Compound conceived and synthesized by Bayer 
or its Affiliates after the Cutoff Date, except if such a conceived compound 
falls within the scope of a patent within the Licensed Technology, Joint 
Inventions or Bayer Technology either (a) issued as of the Cutoff Date, or 
(b) 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;

           (iii)  a compound other than those described in subsections (i) or 
(ii) above which is conceived and synthesized by Bayer or its Affiliates or 
by a third party under the authority of Bayer after the end of the Research 
Program independently of the

                                       -3-

<PAGE>

intellectual property developed through the activities set forth in 
subsections (i)-(iii) of Section 1.8, 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.

     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 market compound engineering 
and encoding, proprietary database and computational technology and/or high 
throughput screening assays.

     1.15  "EXCLUSIVITY PERIOD" shall mean:

           1.15.1  with respect to all Library Compounds contained in any 
Bayer Random Library, 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  [ * * * ]   the 
Notice Date, or such later date as may  be established under Section 2.4.1 of 
the Random Library Agreement; and

          1.15.2  for each Designated Compound, that period commencing with 
the decoding of such Designated Compound and continuing until  [ * * * ]   
within the Existing Patent Rights and/or Future Patent Rights claiming such 
Designated Compound.

          1.15.3  with respect to any Focused Library screened by 
Pharmacopeia in connection with the Research Program, for all Library 
Compounds contained in that Library, that period commencing on the first day 
of the Initial Term and continuing until  [ * * * ]  in such Focused 
Library.

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

[ * * *  Confidential Treatment Requested. ]

                                       -4-

<PAGE>

     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 mean the period commencing on the earlier of 
(i) July 1, 1996, or (ii) the date on which the Research Plan is adopted for 
the first Designated Field pursuant to Section 2.1(e) below, and terminating 
on the second anniversary of the date specified in (ii).

     1.19  "LEAD COMPOUND" shall have the meaning set forth in Section 6.2.4.

     1.20  "LIBRARY" shall mean any chemical compound library prepared by or 
on behalf of Pharmacopeia. Libraries shall be comprised of two types, as 
follows:

           1.20.1  "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, pursuant to the Random Library Agreement.

           1.20.2  "FOCUSED LIBRARY" shall mean any library prepared by 
Pharmacopeia specifically for screening in the Research Program based on (i) 
structures with activity against the Designated Target disclosed by Bayer to 
Pharmacopeia pursuant to Section 2.1(b) or Section 2.2.2(c) below, (ii) 
proprietary structure-activity relationship information relating to the 
structures in (i) above, supplied by Bayer to Pharmacopeia, or (iii) 
proprietary information of Pharmacopeia based on (i) or (ii) above.

     1.21  "LIBRARY COMPOUND" shall mean any compound which is or was 
contained in a Library prepared and screened by Pharmacopeia in connection 
with the Research Program.

     1.22  "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.

           1.22.1  "EXISTING PATENT RIGHTS" shall mean (i) all patents and 
patent applications existing as of the Effective Date that claim any 
Designated Compound or method of use or process for the synthesis thereof or 
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 a patent in 
subsection (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.

                                       -5-

<PAGE>

     1.22.2  "FUTURE PATENT RIGHTS" shall mean (i) all patents and patent 
applications claiming a Designated Compound or method of use or process for 
the synthesis thereof or composition-of-matter thereof conceived by 
Pharmacopeia during the term of the Research Program or jointly with Bayer 
and/or its Affiliates or Sublicensees during the term of the Research 
Program, (ii) all patents and patent applications claiming a Derivative 
Compound or method of use or process for the synthesis thereof or 
composition-of-matter thereof conceived by Pharmacopeia during the term of 
the Research Program or jointly with Bayer and/or its Affiliates or 
Sublicensees during the term of the Research Program, and (iii) any 
divisions, continuations, continuations-in-part, reissues, reexaminations, 
extensions or other governmental actions which extend any of the subject 
matter of a patent, and any substitutions, confirmations, registrations, 
revalidations, or additions of any of the foregoing, in each case, which is 
owned or  controlled, in whole or in part, by license, assignment or 
otherwise by Pharmacopeia during the term of this Agreement.

     1.22.3  "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 in part by Pharmacopeia by 
license, assignment or otherwise, in each case, which is necessary for  the 
development, manufacture, use, sale or commercialization of Agreement 
Compounds and Agreement Products, in each case, to the extent Pharmacopeia 
has the right to license or sublicense the same, and subject to any 
limitations or prohibitions of any license or sublicense. Excluded from 
Existing Know-How are any inventions otherwise included in the definition of 
any Existing Patent Rights in this Agreement.

     1.22.4  "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 in part by license, assignment or otherwise or 
jointly with Bayer and/or its Affiliates during the term of the Research 
Program, in each case, which is necessary for the development, manufacture, 
use or sale or commercialization of Agreement Compounds and Agreement Products. 
Excluded from Future Know-How are any inventions otherwise included in the 
definition of any Future Patent Rights in this Agreement.

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

     1.24  "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.

                                       -6-

<PAGE>

     1.25  "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 program charge backs, 
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.

     1.26  "NOTICE DATE" shall have the meaning set forth in Section 1.15.1 
of this Agreement.

     1.27  "OTHER COMPOUND" shall mean any Library Compound in a Focused 
Library screened by or on behalf of Bayer pursuant to Section 4.3.1 which 
demonstrates activity outside the Designated Field that Bayer has designated 
pursuant to Section 4.4. It is understood that Other Compounds shall not 
include compound(s) which also have activity within the Designated Field.

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

                                       -7-

<PAGE>

     1.29  "RANDOM LIBRARY AGREEMENT" means that certain Random Library 
Agreement entered into by the parties on even date herewith.

     1.30  "RESEARCH PLAN" shall have the meaning set forth in Section 2.3.

     1.31  "RESEARCH PROGRAM" shall include the activities and items set 
forth in Sections 2.2.1 and 2.2.2 of this Agreement.

     1.32  "RESEARCH STEERING COMMITTEE" or "RSC" shall have the meaning set 
forth in section 3.1 below.

     1.33  "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 an Agreement Compound, or to 
make, have made, use, have used, import, have imported, offer for sale, have 
sold and/or sell an 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 Products 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                                 
                                RESEARCH PROGRAM

     2.1  SELECTION OF DESIGNATED TARGET.  The molecular target(s) which will 
be the subject of the Research Program shall be agreed upon by the parties in 
accordance with the following procedures:

          (a)  PROPOSED MOLECULAR TARGET.  Bayer shall have the right to 
propose with notice to Pharmacopeia on or before July 1, 1996, a specific 
molecular target for study in the Research Program, and Pharmacopeia shall 
notify Bayer within seven (7) days of Pharmacopeia's receipt of such notice 
whether such target may be pursued in the Research Program without a conflict 
with or breach of Pharmacopeia's existing agreements with third parties.

          (b)  BAYER INFORMATION.  After receipt of a notice from 
Pharmacopeia indicating that the proposed target may be pursued in the 
Research Program, Bayer shall disclose to Pharmacopeia the structures of any 
proprietary Bayer compounds known to have activity against such molecular 
target, and any available structure-activity data

                                       -8-

<PAGE>

relating thereto, a description of the assays Bayer wishes to have 
Pharmacopeia conduct in connection with the Research Program, and other 
relevant information (e.g., any reagents which Bayer will provide 
Pharmacopeia in connection with the Research Program and the like), and such 
further information as Pharmacopeia may reasonably request from Bayer with 
regard to the activities Bayer would like Pharmacopeia to conduct in the 
Research Program.

          (c)  NOTICE FROM PHARMACOPEIA.  Within twenty-one (21) days of 
receipt of all such information, Pharmacopeia shall notify Bayer whether (i) 
Pharmacopeia believes it is feasible to perform the Research Program with 
respect to the structures and molecular target proposed by Bayer, (ii) the 
number of Pharmacopeia full-time equivalent ("FTE") research positions 
necessary for the conduct of a Research Program with respect to the proposed 
molecular target, and (iii) if Pharmacopeia wishes to pursue such proposed 
target in the Research Program.

          (d)  AGREED TERMS.  In the event that Pharmacopeia provides notice 
that it is willing to pursue the structures and molecular target proposed by 
Bayer, such target shall be deemed a "Designated Target," and the parties 
shall promptly meet to (i) agree on the number of FTE research positions for 
the Research Program, which number shall not be less than an average of 
[ * * * ]  FTE's unless otherwise agreed by the parties, (ii) define the 
Designated Field for such Designated Target, and (iii) define criteria for 
the specificity and potency of a Designated Compound, and agree on whether an 
appropriate IN VIVO model exists for the Designated Target.

          (e)  RESEARCH PLAN.  After the parties agree on each of the items 
set forth in subsection (d) above, the parties shall promptly discuss and 
agree on a written Research Plan for the conduct of the Research Program.

     2.2  RESEARCH PROGRAM ACTIVITIES.  Subject to the terms and conditions 
set forth herein, the parties shall conduct research under the Research Plan 
with respect to Agreement Compounds on a collaborative basis with the goal of 
identifying Lead Compounds that may be developed into Agreement Products. 
Each party shall use its diligent efforts to conduct the Research Program in 
accordance with the Research Plan, within the time schedules contemplated 
therein, with a view towards identifying Lead Compounds in a timely fashion. 
Diligent efforts for Bayer shall be those efforts it would use for similar 
research work for its own compounds of similar value and status.

          2.2.1  PHARMACOPEIA RESPONSIBILITIES.

                 (a)  REASONABLE EFFORTS.  Pharmacopeia shall use reasonable 
efforts to perform the Research Program with the goal of optimizing 
opportunities to identify Lead Compounds by generating Focused Libraries and 
screening such Libraries in view of the Pharmacopeia personnel resources to 
be devoted to the Research Program in accordance with the Research Plan;

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                 (b)  DISCLOSURES.  During the term of the Research Program, 
Pharmacopeia shall keep the RSC fully informed of its activities in the 
Designated Field including, without limitation, by providing the RSC with 
data and information regarding Agreement Compounds, and structures thereof, 
and biological assays developed  by Pharmacopeia relating to the Designated 
Field;

                 (c)  STAFFING.  During the Initial Term, Pharmacopeia will 
provide an average of  [ * * * ]  full-time equivalent ("FTE") research 
positions to conduct the Research Program, or such greater number of FTE 
positions as may be agreed pursuant to Section 2.1(d) above or Sections 2.4.2 
or 2.5.2 below; and

                 (d)  THIRD PARTY LICENSES.  Subject to Section 2.5.4(b), 
Pharmacopeia may acquire licenses to the intellectual property or technology 
of third parties necessary for the performance of the Research Program.

          2.2.2  BAYER RESPONSIBILITIES.

                 (a)  REASONABLE EFFORTS.  Bayer shall use reasonable efforts 
to provide Pharmacopeia with support and assistance in the conduct of the 
Research Program;

                 (b)  DISCLOSURES.  During the term of the Research Program, 
Bayer shall keep the RSC informed of its activities in the Designated Field, 
except with respect to Excluded Products, including, without limitation, by 
providing the RSC with data and information regarding Agreement Compounds, 
and structures thereof, and assays relating to the Designated Target 
developed and used by Bayer; provided, Bayer need not disclose to 
Pharmacopeia information or data which does not directly relate to the goals 
of the Research Program; and

                 (c)  BAYER STRUCTURES.  Bayer may disclose to Pharmacopeia 
structures proprietary to Bayer, which Bayer synthesized and demonstrated to 
have activity in the Designated Field, as shown by contemporaneous 
documentation, and proprietary structure-activity relationship data relating 
thereto, which the RSC may use to design Libraries for screening in 
connection with the Research Program.

     2.3  RESEARCH PLAN.  The parties shall adopt a written overall plan for 
the research the parties will conduct in the Designated Field (the "Research 
Plan") pursuant to Section 2.1(d) above. The RSC shall review the Research 
Plan on an ongoing basis and may make changes to the Research Plan; provided, 
however, the Research Plan shall not be modified except as mutually agreed by 
Pharmacopeia and Bayer.

     2.4  EXTENSION OF RESEARCH PROGRAM TERM.

          2.4.1  OPTION TO EXTEND.  Bayer shall have the right to extend the 
term of the Research Program  [ * * * ]  beyond the Initial Term. To

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extend the Research Program beyond the Initial Term, Bayer must notify 
Pharmacopeia no later than six (6) months prior to the second anniversary of 
the commencement of the Initial Term, and if Bayer so notifies Pharmacopeia, 
the parties shall negotiate the terms of any such extension in good faith.

          2.4.2  EXTENSION TERMS.  During the  [ * * * ]  term of the 
Research Program (if any), Pharmacopeia will provide a minimum of  [ * * * ]  
full-time equivalent research positions. Notwithstanding the foregoing, if 
during the year immediately preceding the applicable extension, the Research 
Program was operating in a broadened scope pursuant to the operation of 
Section 2.5.2, at the request of Bayer, Pharmacopeia will provide up to  
[ * * * ]  additional FTE research positions, over and above the  [ * * * ]  
average FTE research positions described above. Bayer shall pay Pharmacopeia 
for each FTE position, calculated as follows:  [ * * * ]  ($[ * * * ]  per 
FTE multiplied by the aggregate increase in the CPI in the period from the 
Effective Date until the date on which each extension term of the Research 
Program commences.

     2.5  OPTIONS TO SUBSTITUTE FIELD OR EXPAND EXISTING RESEARCH PROGRAM.

          2.5.1  OPTION TO SUBSTITUTE FIELD.  After the first anniversary of 
the commencement of the Initial Term, or earlier with the consent of the RSC, 
Bayer shall have the option of discontinuing the activities of the Research 
Program with respect to the initial Designated Field, and redirecting the 
Research Program towards another mutually agreed molecular target.

                 (a)  EXERCISE OF OPTION.  To exercise such option, Bayer 
shall provide Pharmacopeia with three (3) months written notice (i) that 
Bayer desires to drop the initial Designated Field from the Research Program, 
and (ii) of the identity of the new field Bayer wishes to pursue. The RSC 
shall promptly meet thereafter to revise the annual Research Plan then in 
effect and develop plans for pursuing any such alternative target.

                 (b)  AGREEMENT AMENDMENTS.  The RSC also shall agree on 
definition of the substitute Designated Field as necessary to establish that 
compounds with activity to a particular molecular target, and products based 
thereon, shall be Agreement Compounds and Agreement Products, respectively, 
for all purposes of this Agreement. The definition of the new field shall be 
commensurate with the scope of the definition for Designated Field and the 
parties shall agree on the terms and conditions defining Libraries to be 
prepared for such field, and the financial terms relating to such Libraries 
and their use. Compounds and products with activity in the new Designated 
Field shall be subject to all applicable Agreement provisions which apply 
with respect to Agreement Compounds and Agreement Products and related 
Libraries in the initial Designated Field MUTATIS MUTANDI. In each case, any 
necessary conforming Agreement amendment shall be promptly completed and 
executed by the parties.

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                                      -11-

<PAGE>

                 (c)  CONTINUED OBLIGATIONS.  In the event that Bayer drops a 
Designated Field from the Research Program because of the successful 
identification of a Designated Compound and directly or indirectly continues 
the development or commercialization of Agreement Compounds or Agreement 
Products directed to such target, Bayer's rights and obligations hereunder 
shall remain in full force and effect, subject to the terms and conditions of 
the Agreement.

           2.5.2  OPTION TO EXPAND EXISTING RESEARCH PROGRAM.  During the 
Initial Term of the Research Program and the  [ * * * ]  extension thereof 
(if any) Bayer shall also have the right to  expand the scope of the Research 
Program with respect to the existing Research Program. To exercise such 
option, Bayer shall provide Pharmacopeia with three (3) months' written 
notice, and Pharmacopeia agrees to use diligent efforts to expand the 
Research Program as rapidly as practicable. Notwithstanding the above, 
Pharmacopeia will not be obligated to commit more than  [ * * * ]  additional 
annual full-time equivalent research positions in total.

          2.5.3  RESEARCH PLAN REVISIONS.  The RSC shall promptly meet after 
any substitution of a new field or expansion of the Research Program to 
revise the Research Plan with respect to the further Research Program 
activities, and the additional amounts which Bayer shall pay to Pharmacopeia 
for the conduct of such further activities in accordance with Section 2.5.4; 
provided, Bayer agrees to pay Pharmacopeia per annum, pro-rated amounts 
subject to Section 2.4.2 for each FTE research position added by Pharmacopeia 
pursuant to this Section 2.5.

          2.5.4  ADDITIONAL EXPENSES.

                 (a)  CAPITAL EXPENDITURES.  In the event that pursuing a
particular Designated Target in the Research Program will require Pharmacopeia
to incur unanticipated reasonable additional out-of-pocket expenses in
connection with the Research Program for facilities alterations or capital
expenditures on specialized equipment, the parties shall agree on the additional
monies which shall be paid to Pharmacopeia by Bayer therefor. In addition, Bayer
shall pay to Pharmacopeia all reasonable direct and indirect expenses incurred
by Pharmacopeia in connection with the hiring or reassignment of personnel with
respect to pursuing a substitute Designated Target pursuant to Section 2.5.1. It
is understood that Pharmacopeia will be the owner of all capital equipment
purchased by Pharmacopeia in connection with the Research Program, whether or
not separately identified in the Research Plan. It is further understood that
Bayer may loan Pharmacopeia, from time to time as the parties agree, certain
capital equipment to be used in the Research Program at Pharmacopeia's facility.

                 (b)  LICENSE COSTS.  In the event that it is necessary for
Pharmacopeia to acquire any third party license specifically for the conduct of
the Research Program in the Designated Field, prior to entering any such license
Pharmacopeia shall notify Bayer of Pharmacopeia's interest in acquiring such
license and the reason therefor.

[ * * *  Confidential Treatment Requested. ]

                                      -12-

<PAGE>

Within thirty (30) days of its receipt of such notice, Bayer shall notify
Pharmacopeia whether it wishes Pharmacopeia to acquire such a license. Bayer
shall pay to Pharmacopeia any amounts paid by Pharmacopeia pursuant to such
license(s) for which Bayer indicates it will be responsible; provided, in the
event such licenses are also used by Pharmacopeia in connection with other
collaborative programs, Bayer shall only be obligated to pay to Pharmacopeia its
pro rata share of such amounts, calculated based on the number of other
collaborative programs in which such intellectual property is used. Pharmacopeia
shall provide Bayer notice of such payment obligations and invoice Bayer for
such costs and Bayer shall pay the invoice within thirty (30) days. In the event
that Bayer declines to pay the costs associated with such a license,
Pharmacopeia shall have no obligation to acquire such a license, and shall have
no liability pursuant to this Agreement for not acquiring such a license or
declining to pursue any research in connection with the Research Program which
would utilize such third party intellectual property or technology.

     2.6  RECORDS; INSPECTION.

          (a)  RESEARCH PROGRAM.  Pharmacopeia and Bayer shall maintain
records of the Research Program (or cause such records to be maintained) in
sufficient detail and in good scientific manner as will properly reflect all
work done and results achieved in the performance of the Research Program
(including all data in the form required under any applicable governmental
regulations and as directed by the RSC). Each party shall allow the other to
have reasonable access to all pertinent materials and data generated by or on
behalf of such party with respect to each Agreement Compound in connection with
the Research Program, as set forth in the Research Plan. It is understood that
Pharmacopeia shall have no obligation to disclose to Bayer any Excluded
Technology. Subject  to Section 2.9, it is understood that Bayer shall have no
obligation to disclose to Pharmacopeia the structures of any pharmaceutically
active compounds in Excluded Products.

          (b)  RESEARCH PROGRAM EXPENDITURES.  Pharmacopeia shall keep
complete, true and accurate books of account and records of the amounts it
expends in connection with the performance of the Research Program. Such books
and records shall be kept at the principal place of business of Pharmacopeia for
at least three (3) years following the termination of the term of the Research
Program. Such records will be open for inspection during such three (3) year
period by a representative or agent of Bayer, at Bayer's expense, for the
purpose of verifying the amounts expended in connection with the Research
Program. Such inspections may be made no more than once each calendar year, at
reasonable times and on reasonable notice. The representative or agent of Bayer
shall sign a customary confidentiality agreement as a condition precedent to
such inspection and shall report to Bayer only whether any discrepancy has been
identified with respect to Research Program expenditures.

     2.7  DESIGNATED FIELD EXCLUSIVITY.  Until the earlier of (a)  [ * * * ]  
after the termination of the Research Program with respect to a particular 
Designated Target, if such termination occurs during the Initial Term, or (b) 
 [ * * * ]  after the end of the Research

[ * * *  Confidential Treatment Requested. ]

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<PAGE>

Program with respect to a particular Designated Target, Pharmacopeia will not
(i) knowingly make compounds or combinatorial libraries for or with any third
person or entity specifically for screening against such Designated Target, (ii)
perform contract screening for or with any third person or entity with respect
to such Designated Target, or (iii) perform for its own account any screening
with respect to such Designated Target. Bayer understands that in the ordinary
course of its business Pharmacopeia provides libraries to third parties for
screening against unidentified targets.

     2.8  POST-RESEARCH PROGRAM ACTIVITIES.  Except as expressly provided
otherwise under the terms of this Agreement, Bayer shall, at Bayer's or its
Affiliates' or Sublicensees' expense, be responsible for conducting all
development of Agreement Compounds and Agreement Products following the
completion of the Research Program, and all commercialization of Agreement
Products which Bayer retains rights to under this Agreement and develops and
commercializes.

     2.9  EXCLUDED PRODUCT.  Until  [ * * * ]  after the end of the Research 
Program, as it 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 14.13 
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 equal to  
[ * * * ]  payments due Pharmacopeia pursuant to Section 6.2.1 which were not 
timely paid to Pharmacopeia (without any obligation to pay interest from the 
date such milestone payments originally should have been made), in addition 
to any other amounts due under the Agreement.

     2.10 TECHNOLOGY TRANSFER.  Subject to Section 5.7 below, to maximize the
success of the Research Program, Pharmacopeia and Bayer shall exchange agreed
information and materials relating to biology and screening technology and
solid-phase chemical synthesis; provided, Pharmacopeia shall have no obligation
to disclose to Bayer any materials or information relating to the Excluded
Technology.

[ * * *  Confidential Treatment Requested. ]

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<PAGE>

                                    ARTICLE 3
                                   MANAGEMENT

     3.1  RESEARCH STEERING COMMITTEE.  Bayer and Pharmacopeia will establish a
Research Steering Committee ("RSC") to oversee, review and coordinate the
conduct of the Research Program, and provide advice regarding prosecution of
patent applications within the Joint Inventions (as defined in Article 9
herein).

     3.2  MEMBERSHIP.  The RSC shall be comprised of an equal number of
representatives from each of Bayer and Pharmacopeia, each party's members
selected by that party. Bayer and Pharmacopeia shall each have four (4)
representatives on such Committee or such other number as the parties may agree.
The initial representatives of each party are listed on Exhibit A hereto.
Pharmacopeia and Bayer may replace its RSC representatives at any time, upon
written notice to the other party. The RSC shall be chaired as agreed by the
parties. From time to time, the RSC may establish subcommittees to oversee
particular projects or activities, and such subcommittees will be constituted as
the RSC agrees.

     3.3  RSC MEETINGS.  During the term of the Research Program, as it may be
extended, the RSC shall meet four (4) times per year at regular intervals, or
more often as agreed by the parties, at such locations as the parties agree. At
such meetings, the RSC will formulate and review the Research Program
objectives, monitor the progress of the Research Program toward those
objectives, and take such other actions as may be specified under this Agreement
or as the parties deem appropriate. With the consent of the parties, other
representatives of Pharmacopeia or Bayer or its Affiliates or Sublicensees may
attend RSC meetings as nonvoting observers. Each party shall be responsible for
all of its own expenses. The first meeting of the RSC shall occur as soon as
practicable after the Effective Date, but in no event later than forty-five (45)
days after the commencement of the Initial Term.

     3.4  DECISION MAKING.  Pharmacopeia and Bayer shall each be entitled to
cast one vote on matters before the RSC. Decisions of the RSC shall be made by
unanimous approval. In the event that unanimity is not achieved within the RSC,
the dispute will be referred to Pharmacopeia's President (or designee of similar
rank) and Bayer's Vice President for Research (or designee of similar rank), who
shall promptly meet and endeavor to resolve the dispute in a timely manner.

     3.5  BAYER RANDOM LIBRARY DESIGN.  In addition to its responsibilities with
respect to the Research Program, the RSC shall be responsible for the selection
and aiding in the design of the Bayer Random Libraries to be provided to Bayer
for screening pursuant to Section 2.1 of the Random Library Agreement.

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<PAGE>

                                    ARTICLE 4
                                    LIBRARIES

     4.1  EXCLUSIVITY PERIODS.

          4.1.1  BAYER RANDOM LIBRARIES.

                 (a)  During the applicable Exclusivity Period, Pharmacopeia 
shall not with respect to any of the Library Compounds described in Section 
1.15.1, use itself (except pursuant to Sections 4.2.2 or 5.5) for screening 
against any target, or knowingly provide any such compounds to any third 
person or entity, except as approved by Bayer in writing.

                 (b)  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 Bayer Random Library, and Pharmacopeia may provide 
such Bayer Random Library to others, subject to the terms and conditions set 
forth in the Random Library Agreement. It is understood that either 
Pharmacopeia or Bayer may seek patent rights on its sole behalf with respect 
to any such Library Compound which such party determines has patentable 
utility, provided that such Library Compound (i) is not a Designated Compound 
or an Active Compound and is 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 of the Random Library Agreement, and 
has not retained rights pursuant to Section 6.2 of the Random Library 
Agreement.

     4.1.2  FOCUSED LIBRARIES.  During the applicable Exclusivity Period set
forth in Section 1.15.3, Pharmacopeia shall not with respect to any of the
Library Compounds contained in a Focused Library provide any such Library
Compounds, to any third person or entity for any purpose, or itself make or use
such Library Compounds or Designated Compounds developed therefrom, as the case
may be, except in connection with the Research Program or as permitted under
Sections 5.5 and 5.6, or as otherwise approved by Bayer in writing.

     4.2  PHARMACOPEIA SCREENING.

          4.2.1  FOCUSED LIBRARIES.  During the term of the Research Program,
Pharmacopeia shall screen Focused Libraries for activity in the Designated
Field. Any compound  identified as having activity against the Designated Target
as a result of such activities shall be considered a Designated Compound for all
purposes of this Agreement.

          4.2.2  BAYER RANDOM LIBRARIES.  During the term of the Research
Program, Bayer shall notify Pharmacopeia whether it wishes Pharmacopeia to
screen any Bayer Random Library in connection with the Research Program.
Pharmacopeia shall not screen

                                      -16-

<PAGE>

any Bayer Random Library in connection with the Research Program without the
prior written consent of Bayer. Bayer understands and agrees that in the event
that Pharmacopeia identifies a Designated Compound from a Bayer Random Library,
such compound shall be subject to the terms and conditions of this Agreement,
including without limitation, the provisions of Section 6.2.1(a) and 6.3.1.

     4.3  BAYER SCREENING.

          4.3.1  FOCUSED LIBRARIES.

                 (a)  During the term of the Research Program, with notice to 
Pharmacopeia, Bayer may request Pharmacopeia to provide Bayer with a copy of 
any Focused Library and, if technically compatible with the 96-well 
microtiter plate format, as reasonably determined by Pharmacopeia, 
Pharmacopeia shall use diligent efforts to provide to Bayer such Focused 
Library within  [ * * * ]  of Bayer's written request. Bayer may screen any 
such Focused Library outside the Designated Field.

                 (b)  Bayer shall pay Pharmacopeia  [ * * * ]  dollars 
($[ * * * ]) for each set of plates for such Focused Library (i.e., two 
copies 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 a target other 
than a Designated Target, and resynthesize up to  [ * * * ]  of  [ * * * ]  
in such Focused Library. 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.

                 (c)  In the event Bayer identifies an Other Compound in such 
a Library, and develops and commercializes an Agreement Compound which is an 
Other Compound or a Derivative Compound thereof, Bayer shall pay to 
Pharmacopeia milestone payments and royalties with respect thereto, pursuant 
to Sections 6.2.1(b) and 6.3.1.

          4.3.2  BAYER RANDOM LIBRARIES.  It is understood and agreed that if
Bayer or its Affiliates of Sublicensees screens any Bayer Random Library
provided to Bayer pursuant to the Random Library Agreement in the existing
Designated Field, and identifies a compound with activity in such  Designated
Field, such compound shall be treated as a Library Compound and a Designated
Compound subject to this Agreement for all purposes, and shall be subject to the
terms and conditions herein, including, without limitation, Sections 6.2.1(a)
and 6.3.1.

     4.4  RIGHT TO DESIGNATE OTHER COMPOUNDS.  Except with regard to Excluded
Products, it is understood that Bayer or its Affiliates or Sublicensees may not
develop or

[ * * *  Confidential Treatment Requested. ]

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<PAGE>

commercialize any Library Compound, or any Derivative Compound developed from a
Library Compound, which has activity outside the Designated Field, unless such
Library Compound has been designated as an Other Compound. Bayer shall have  the
right to designate any Library Compound in a Focused Library as an Other
Compound as follows:

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

          4.4.2  IDENTIFICATION BY BAYER.  In the event that Bayer or its
Affiliates or Sublicensees identifies, without decoding by Pharmacopeia pursuant
to Section 4.4.1 above, a particular Library Compound with activity in a
particular biological assay outside the Designated Field, Bayer shall give
Pharmacopeia notice identifying such Library Compound and indicating that the
Library Compound has activity outside the Designated Field. Such Library
Compound shall be designated an Other Compound as of the date of Pharmacopeia's
receipt of such notice.

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

                                    ARTICLE 5
                                    LICENSES

     5.1  LICENSE TO BAYER.  Subject to the terms and conditions of this
Agreement, Pharmacopeia agrees to grant, and hereby grants, to Bayer and its
Affiliates a worldwide, exclusive license under the applicable Licensed
Technology 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 based on Designated
Compounds or Derivative Compounds thereof in the Designated Field, and based on
Other Compounds or Derivative Compounds thereof outside the Designated Field. It
is understood that such licenses shall include the right to discover and develop
Agreement Compounds and Agreement Products and to conduct drug research in the
Designated Field after the term of the Research Program during the term of this
Agreement.

     5.2  SUBLICENSES.  Subject to the terms and conditions of this Agreement,
Bayer (but not its Affiliates) shall have the right to sublicense the rights
granted in Section 5.1 above; provided, Bayer shall not transfer any Bayer
Random Library or Focused 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,

                                      -18-

<PAGE>

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

     5.3  THIRD PARTY RIGHTS.

          5.3.1  OVERLAPPING RIGHTS.  It 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 5. 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 5 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.

          5.3.2  NO LIABILITY.  It is understood and agreed that even if 
Pharmacopeia complies with its obligations under this Agreement, that 
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; provided, that unless Bayer is 
damaged as a proximate result of a material breach by Pharmacopeia of the 
terms of Article 4 or any of the representations and warranties in Article 
11, then Pharmacopeia shall have no liability under this Agreement with 
respect to any such conflict.

     5.4  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 nonexclusive,
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 (i) based on Designated Compounds or
Derivative Compounds thereof, in the Designated Field, and (ii) based on Other
Compounds or Derivative Compounds thereof, outside the Designated Field. It is
understood and agreed that such sublicenses do not include the right to create,
make or have

                                      -19-

<PAGE>

made encoded combinational libraries, tags, markers or other encoding
compositions, or use methods or processes relating to encoded combinatorial
libraries, tags, markers, or other encoding compositions, or 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.

     5.5  RESEARCH LICENSE.  Notwithstanding Section 5.1 above, Pharmacopeia
shall retain the right under the Licensed Technology to make, have made and use
Library Compounds for it 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 or which would jeopardize the commercial or research value of the
Bayer Technology.

     5.6  PHARMACOPEIA RESEARCH PROGRAM.  Pharmacopeia shall have the
nonexclusive right to use during the Research Program intellectual property of
Bayer, such as reagents, as reasonably necessary to assay compounds in Libraries
for activity in the Designated Field. Bayer shall be responsible for the payment
of all amounts due third parties for Pharmacopeia's use of such intellectual
property in connection with the Research Program. As a condition precedent to
such use Pharmacopeia will execute any consents or sublicenses required by any
Bayer licensor; provided, Pharmacopeia shall not be required to execute any
unreasonable consents or licenses and will not be in breach of this Agreement
for failure to do so.

     5.7  TECHNOLOGY TRANSFER LICENSE.  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 2.10 above which is necessary for the conduct
of the Research Program.

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

     5.9  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 5.1 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.

                                      -20-

<PAGE>

                                    ARTICLE 6
                                    PAYMENTS

     6.1  COLLABORATION FUNDING.

          6.1.1  RESEARCH PROGRAM FUNDING.  Bayer agrees to pay to Pharmacopeia
research funding with respect to the Research Program, in the following amounts:

               PERIOD            AMOUNT
               ------            ------
               Year 1         $2.75 Million
               Year 2         $2.75 Million

The above amounts are based on an average of  [ * * * ]  Pharmacopeia FTEs 
per year. In the event that the parties agree, pursuant to Section 2.1(d) 
above, that the Research Program requires more than  [ * * * ]  Pharmacopeia 
FTEs, the above amounts will be increased by  [ * * * ]  per FTE per year. If 
a substitute Designated Field has been added to the Research Program pursuant 
to Section 2.5.1, or the Research Program is expanded pursuant to 
Section 2.5.2, Bayer shall pay to Pharmacopeia the additional amounts 
specified in Section 2.5, when due. If the Research Program is extended 
pursuant to Section 2.4, Bayer shall pay to Pharmacopeia Research funding to 
be agreed by the parties for such additional period.

          6.1.2  ANNUAL PAYMENTS.   The amounts to be paid under Sections 
2.4, 2.5, and 6.1.1 above with respect to each twelve (12) month period 
shall be paid annually, and shall not be creditable against any other amounts 
due under this Agreement. The funding for the first year of the Research 
Program shall be paid to Pharmacopeia within thirty (30) days after the first 
day of the Initial Term. Subsequent annual payments shall be made on or 
before the applicable yearly anniversary of the Initial Term. All such 
payments shall be non-refundable.

          6.1.3  RECORDS; INSPECTION.  Pharmacopeia shall keep complete, true 
and accurate books of account and records for the purpose of determining the 
allocation of research funding under Section 6.1.1 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 Pharmacopeia has no reasonable objection, solely for 
the purpose of verifying research funding expenditures 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 
6.1.3 shall be at the expense of Bayer, solely for the purpose of verifying 
the accuracy of the expenditures. The public accounting firm employees shall 
sign a customary confidentiality agreement as a condition precedent to their 
inspection, and shall report to

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                                      -21-

<PAGE>

Bayer only that information which would be contained in a properly prepared
research funding expenditure report by Pharmacopeia.

     6.2  MILESTONE PAYMENTS.

          6.2.1  AGREEMENT PRODUCTS.

                 (a)  ACTIVE IN THE DESIGNATED FIELD.  Subject to Sections 
6.2.2 and 6.2.3 below, Bayer agrees to pay to Pharmacopeia the following 
amounts upon completion by Bayer or its Affiliates, Sublicensees or other 
designees of each achievement of each of the following milestones with 
respect to Agreement Compounds which are Designated Compounds or Derivative 
Compounds thereof (including Agreement Products), but not with respect to 
Excluded Products. Bayer shall have no obligation to pay any of the following 
milestone payments more than one (1) time with respect to Agreement Compounds 
or Agreement Products with activity against a particular molecular target in 
the Designated Field, regardless of how many applicable Agreement Products 
are commercialized:

               Milestones                                            Amount
          -------------------------                                  ------
     Identification of a 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 NDA or foreign equivalent in any Major Country        $

     First approval of an NDA or foreign equivalent in any
     Major Country                                                   $

                                                      Total          $


                 (b)  ACTIVE OUTSIDE THE DESIGNATED FIELD.  Subject to 
Section 6.2.3 below, Bayer agrees to pay to Pharmacopeia the following 
amounts upon achievement by Bayer or its Affiliates, Sublicensees or other 
designees of each of the following milestones with respect to Agreement 
Compounds which are Other Compounds or

[ * * *  Confidential Treatment Requested. ]

                                      -22-

<PAGE>

Derivative Compounds thereof (including Agreement Products), but not with
respect to Excluded Products, as follows:

               Milestones                                            Amount
          -------------------------                                  ------
     Identification of a 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 NDA or NDA equivalent in any Major Country            $

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

                                                      Total          $


          6.2.2  REDUCED MILESTONE PAYMENTS.  Notwithstanding Section 6.2.1 
above, in the event that a Derivative Compound with activity in the 
Designated Field which Bayer elects to develop (i) is conceived later than  
[ * * * ]  years after the end of the Research Program, as it may be 
extended, but before  [ * * * ]  years following the end of the Research 
Program, as it may be extended, 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 only be obligated 
to pay to Pharmacopeia  [ * * * ]  percent  [ * * * ]  of the milestone 
payment above with respect to such Derivative Compound (or a corresponding 
Agreement Product).

          6.2.3  EXCLUSIONS.  Notwithstanding Section 6.2.1 above, in the 
event that any Derivative Compound which Bayer elects to develop (i) is 
conceived later than  [ * * * ]  years after the end of the Research Program, 
as it may be extended, 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 milestone payments above with respect to such Derivative 
Compound (or a corresponding Agreement Product).

          6.2.4  LEAD COMPOUND.  A Lead Compound shall be deemed to have been 
identified at such time as Bayer, by action of the International Research 
Committee ("IRC")

[ * * *  Confidential Treatment Requested. ]
                                      -23-
<PAGE>

or its successor (i) identifies a Designated Compound with the potency, IN 
VITRO specificity and, if applicable, IN VIVO activity in an animal model, in 
each case, as agreed by the parties pursuant to Section 2.1(d) above, or
(ii) approves a strategic project based on an Other Compound. In any event, 
however, if Bayer, or any Affiliate, 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.

          6.2.5  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 International Product
Development Committee ("IPDC") 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 and/or 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.

          6.2.6  PAYMENTS.  All payments made to Pharmacopeia by Bayer 
pursuant to this Section 6.2 shall be due within thirty (30) days after the 
occurrence of the corresponding milestone and shall be nonrefundable and 
noncreditable. It is understood that the milestone payments set forth above 
shall be made with respect to each Agreement Compound and Agreement Product 
with activity against a particular molecular target; provided, however, that 
if Bayer ceases all development of a particular Agreement Compound (or 
corresponding Agreement Product) after having made payments with respect to 
such Agreement Compound and Agreement Product under this Section 6.2 on the 
accomplishment of milestones specified herein, there shall be no payment due 
upon the accomplishment of those same milestones with respect to the next 
Agreement Compound or Agreement Product hereunder that is directed at the 
same molecular target. Amounts due with respect to milestones achieved with 
respect to such subsequent Agreement Compound or Agreement Product which were 
not previously paid with respect to an earlier Agreement Compound or 
Agreement Product shall be paid pursuant to this Section 6.2.

     6.3  ROYALTIES TO PHARMACOPEIA.

          6.3.1  BASE ROYALTY.  Bayer shall pay to Pharmacopeia running 
royalties equal to  [ * * * ]  percent  [ * * * ]  of the aggregate Net Sales 
made by Bayer and its Affiliates and Sublicensees of Agreement Products, 
except that no royalties will be payable with respect to Excluded Products.

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                                      -24-

<PAGE>

          6.3.2  ROYALTY RATE REDUCTION FOR DERIVATIVE COMPOUNDS. 
Notwithstanding Section 6.3.1 above, in the event that a Derivative Compound 
with activity in the Designated Field which Bayer elects to develop (i) is 
conceived later than  [ * * * ]  years after the end of the Research Program, 
as it may be extended, but on or before  [ * * * ]  years following the end 
of the Research Program, as it may be extended, 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 only be obligated to pay to Pharmacopeia  [ * * * ]  percent  [ * * * ] 
 of the royalties above with respect to such Derivative Compound (or a 
corresponding Agreement Product).

          6.3.3  EXCLUSIONS.  Notwithstanding Section 6.3.1 above, in the 
event that any Derivative Compound which Bayer elects to develop (i) is 
conceived later than  [ * * * ]  years after the end of the Research 
Program, as it may be extended, 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 royalties above with respect to such Derivative 
Compound (or a corresponding Agreement Product).

          6.3.4  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 6.3, 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 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 on 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 shall be  
[ * * * ]  the royalty due pursuant to Section 6.3.1 or 6.3.2, as the case 
may be.

          6.3.5  SINGLE ROYALTY; NONROYALTY SALES.  No royalty shall be payable
under this Section 6.3 with respect to sales of Agreement Products among Bayer
or its Affiliates

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                                      -25-

<PAGE>

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.

          6.3.6  ROYALTY TERM.  Bayer's obligation to pay royalties to 
Pharmacopeia under this Section 6.3 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 or selling the applicable 
Agreement Product in the applicable country in the absence of the license 
grants in this Agreement.

          6.3.7  THIRD PARTY ROYALTIES.  Bayer shall be responsible for the
payment of any royalties due to third parties upon the manufacture, use,
marketing, sale or distribution of Agreement Products by Bayer or its Affiliates
or Sublicensees (except as to 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 Focused
Libraries or decoding of Library Compounds.

     6.4  EQUITY INVESTMENT.  Simultaneously with the execution of this
Agreement Pharmacopeia and Bayer shall execute a Common Stock Purchase Agreement
in the form attached hereto as Exhibit C (the "Purchase Agreement") providing
for the purchase by Bayer of shares of Common Stock of Pharmacopeia, on the
terms and conditions therein.

                                    ARTICLE 7
                           PAYMENTS; BOOKS AND RECORDS

     7.1  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 6.3 above.
Concurrently with the making of such reports, Bayer shall pay to Pharmacopeia
royalties due at the rates specified in Section 6.3.

     7.2  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

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                                      -26-

<PAGE>

York, New York, on the date such payment is due, calculated on the number of
days such payment is delinquent.

     7.3  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.

     7.4  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 7.4 shall be at the expense of Pharmacopeia, unless a variation or error
producing an increase exceeding five percent (5%) of the amount stated for any
period covered by the inspection is established in the course of any such
inspection, whereupon all reasonable 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 a 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.

     7.5  TAX MATTERS.

          7.5.1  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

                                      -27-

<PAGE>

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.

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

                                    ARTICLE 8
                                  DUE DILIGENCE

     8.1  DUE DILIGENCE.  The selection of Designated Compounds, Other
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 at
least one Agreement Product in the Designated Field as expeditiously as
practicable and take such other actions as are necessary to obtain government
approvals to market each Agreement Product in the Major Countries and other
significant markets throughout the world, and thereafter to promote each
Agreement Product and meet the market demand therefor in such markets.

     8.2  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:

          8.2.1  DESIGNATED COMPOUNDS.  With respect to Agreement Compounds
which are Designated Compounds or Derivative Compounds thereof: (i) description
of the status of the research and development activities conducted with respect
to each Agreement Compound; and (ii) the status of all patent applications
claiming such Agreement Compounds.

          8.2.2  OTHER COMPOUNDS.  With respect to Agreement Compounds which
are Other Compounds or Derivative Compounds thereof: (i) identification, on a
coded basis, of all targets against which each Agreement Compound demonstrated
activity (i.e., with targets designated by a random 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.

                                      -28-

<PAGE>

The reports subject to  this Section 8.2 shall contain sufficient information to
allow Pharmacopeia to monitor Bayer's compliance with this Agreement, including
without limitation, Bayer's obligations with respect to the accomplishment of
the milestones set forth in Section 6.2.1. 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 information provided under this Section 8.2 shall be deemed
Confidential Information of Bayer.

     8.3  LICENSE BACK. In the event that Bayer agrees to allow Pharmacopeia to
acquire rights to any Agreement 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
Agreement Compound or Agreement Product.

     8.4  LICENSE TO LIBRARY COMPOUNDS FROM A BAYER RANDOM LIBRARY AFTER THE
EXCLUSIVITY PERIOD.  Following the Exclusivity Period with respect to a Library
Compound from a Bayer Random Library, for each such Library Compound which is
not a Designated Compound, in the event that Pharmacopeia determines that any
such Library Compound, which is claimed in a Bayer patent application or patent
claiming a Designated Compound, has a biological activity distinct from the
utility claimed in such patent application or patent, Pharmacopeia may provide
Bayer with evidence reasonably demonstrating that such Library Compound has such
distinct activity. Bayer shall have a period of ninety (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 grant 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.

     8.5  REGULATORY FILINGS.  If Pharmacopeia acquires rights from Bayer with
respect to any Agreement Compound or Agreement Product pursuant to Section 8.3
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 Agreement 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.

                                      -29-

<PAGE>

                                    ARTICLE 9
                              INTELLECTUAL PROPERTY


     9.1  OWNERSHIP OF INVENTIONS.  Title to all inventions and other
intellectual property made by employees of Bayer or its Affiliates, but not
Pharmacopeia, in connection with and arising out of the Research Program ("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, in connection with and arising out of with the Research Program
("Pharmacopeia Inventions") shall be deemed owned by Pharmacopeia. Title to all
inventions and other intellectual property made jointly by employees of Bayer or
its Affiliates and Pharmacopeia in connection with and arising out of the
Research Program ("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
14.13.

     9.2  PATENT PROSECUTION.

          9.2.1  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 and 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 Section 9.2.3 and 9.2.4, 
Pharmacopeia 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 (except those claiming Designated 
Compounds or Derivative Compounds originating in Focused Libraries or the use 
of such Designated Compounds or Derivative Compounds) and conducting any 
interferences, re-examinations, reissues and oppositions relating to such 
Licensed Technology.

                                      -30-

<PAGE>

                 (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, oppositions or requests for patent 
term extension or governmental equivalents thereto relating to Bayer 
Inventions and relating to Joint Inventions claiming Designated Compounds or 
Derivative Compounds originating in Focused Libraries or the use of such 
Designated Compounds or Derivative Compounds.

          9.2.2  PHARMACOPEIA FAILURE TO PROSECUTE.  Pharmacopeia may elect upon
ninety (90) days prior notice to discontinue prosecution of any patent
applications filed pursuant to Section 9.2.1 (a) or (b) above and/or not to file
or conduct any further activities with respect to the patent applications or
patents subject to such Sections. In the event Pharmacopeia declines to file or
having filed fails to further prosecute or maintain any patent applications or
patents (i) subject to Section 9.2.1(a) above which disclose or claim activity
in the Designated Field, or (ii) subject to Section 9.2.1(b) above, or conduct
any interferences, re-examinations, reissues, or oppositions, then, subject to
Pharmacopeia's agreements with third parties, 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.

          9.2.3  COOPERATION.  Each of Bayer and Pharmacopeia shall keep the
other fully informed as to the status of patent matters described in this
Article 9, 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 other 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 term of the Research
Program; and (ii) the pendency of any patent applications claiming Joint
Inventions subject to this Section 9.2, to coordinate, discuss, review and
implement patent filing and prosecution strategy.

          9.2.4  COSTS.  Responsibilities for costs incurred under this
Article shall be as follows:

                 (i)     Subject to subsection (iii) below, Pharmacopeia shall
                         pay all costs pursuant to Section 9.2.1(a);

                (ii)     Bayer shall pay all costs incurred pursuant to Section
                         9.2.1(c);


                                      -31-

<PAGE>

               (iii)     The parties shall equally share the costs incurred
                         pursuant to Section 9.2.1(b); and any costs incurred by
                         Pharmacopeia in connection with the activities
                         undertaken pursuant to Section 9.2.1(a) with respect to
                         patent applications or patents disclosing or claiming
                         Focused Libraries or Library Compounds therein, or
                         methods of use thereof; and

                (iv)     Notwithstanding Section 9.2.4(iii) above, with respect
                         to total out-of-pocket expenses (including, without
                         limitation, patent attorney and agent fees) associated
                         with Pharmacopeia's activities pursuant to Sections
                         9.2.1(a) and (b) above, Pharmacopeia shall have no
                         obligation to incur in any calendar year more than the
                         greater of (i) $[ * * * ]  per calendar year, or 
                         (ii)  [ * * * ]  percent  [ * * * ]  of the 
                         milestones received by Pharmacopeia from Bayer 
                         pursuant to Section 6.2.1 herein in such calendar 
                         year. Pharmacopeia shall provide Bayer quarterly 
                         reports of the expenses incurred in connection with 
                         such activities to keep Bayer apprised of whether 
                         the patent activities are likely to incur costs in 
                         excess of those set forth in the preceding sentence. 
                         If it appears that the expenses would exceed such 
                         limit, Pharmacopeia shall provide Bayer notice thereof,
                         and within thirty (30) days of such notice Bayer 
                         shall notify Pharmacopeia whether it will reimburse 
                         Pharmacopeia for such excess amounts incurred by 
                         Pharmacopeia in connection with such activities. 
                         If Bayer so notifies Pharmacopeia then Pharmacopeia 
                         shall invoice such amounts and Bayer shall promptly 
                         pay such invoice(s).

          9.2.5   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 during the term of
this Agreement with respect to any Agreement Compounds.

     9.3  ENFORCEMENT AND DEFENSE.

          9.3.1  ENFORCEMENT.  Each party shall promptly notify the other of
its knowledge of any potential infringement of the Licensed Technology by a
third party. Pharmacopeia has the right, but not the obligation, to take
reasonable legal action necessary to protect the Licensed Technology described
in Sections 9.2.1(a) and (b) against infringements by third parties. If within
six (6) months following receipt of such notice from Bayer, Pharmacopeia fails
to take such action to halt a commercially significant infringement, Bayer
shall, in its sole discretion, have the right, at its expense, to take such

[ * * *  Confidential Treatment Requested. ]

                                   -32-

<PAGE>

action as it deems warranted in its own name or in the name of Pharmacopeia or
jointly to cease any infringement with respect to Licensed Technology (i)
subject to Section 9.2.1(a) which claims Focused Libraries or Library Compounds
therein, or methods of use thereof, or (ii) subject to Section 9.2.1(b). Each
party agrees to render such reasonable assistance as the prosecuting party may
request. Costs of maintaining any such action and damages recovered therefrom
shall be paid by and belong to the party bringing the action. Bayer shall have
the right to enforce patents described in Section 9.2.1(c) in its sole
discretion, at its sole expense.

          9.3.2   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) and 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.

     9.4  GRANT BACK.

          9.4.1   COMPOUNDS BASED ON PHARMACOPEIA PROPRIETARY INFORMATION.  In
the event that Pharmacopeia determines that any Library Compound in a Focused
Library of the type defined in Section 1.20.2(iii) above, which Library Compound
(i) is not a Designated Compound or Other Compound, and (ii) is claimed in a
Bayer patent application or patent claiming a Designated Compound or Other
Compound, has a biological activity distinct from the utility disclosed in such
patent application or patent, and does not have the utility disclosed by Bayer,
Pharmacopeia may notify Bayer, and provide evidence reasonably demonstrating
that such Library Compound does not have the utility disclosed by Bayer. Bayer
shall have a period of ninety (90) days from receipt of such notice in which to
provide Pharmacopeia with evidence reasonably demonstrating that such Library
Compound has the utility disclosed in the patent application or patent. In the
event that Bayer fails to provide such evidence to the contrary within such
period, Pharmacopeia shall have the right to use such compound for such utility.

          9.4.2   PROCESS TECHNOLOGY.  Bayer shall grant and hereby grants to
Pharmacopeia a non-exclusive, royalty-free, worldwide, license under Bayer's
interest in the Joint Inventions relating to any chemical processes, synthetic
or otherwise, for the purpose of designing and preparing chemical libraries.

                                      -33-

<PAGE>

                                   ARTICLE 10
                                 CONFIDENTIALITY

     10.1  CONFIDENTIAL INFORMATION.  Except as otherwise 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 10, disclose to any third party or use for any 
purpose any confidential information furnished to it by the disclosing party 
hereto 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.

     10.2  PERMITTED USE AND DISCLOSURES.  Each party hereto may use or disclose
information disclosed to it by the other party to the extent such information is
included in the Licensed Technology or the Bayer Technology, as the case may be,
and to the extent such use or disclosure is reasonably necessary and permitted
in the exercise of such rights granted hereunder in filing or prosecuting patent
applications, prosecuting or defending litigation, complying with applicable
governmental regulations or court order 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 by
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 its reasonable
best efforts to secure confidential treatment of such information in
consultation with the other party prior to its disclosure (whether through
protective orders or otherwise) and disclose only the minimum necessary to
comply with such requirements.

[ * * *  Confidential Treatment Requested. ]

                                      -34-

<PAGE>

     10.3  NONDISCLOSURE OF TERMS.  Each of the parties hereto agrees not to
disclose the terms of this Agreement to any third party without the prior
written consent of the other party hereto, which consent shall not be
unreasonably withheld, 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,
Bayer and Pharmacopeia may make public statements regarding the progress of the
Research Program and the achievement of milestones and fees with respect
thereto, following consultation and mutual agreement, the consent of neither
party to be unreasonably withheld. 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.

     10.4  PUBLICATION.  Any manuscript, abstract or presentation (including
information to be presented verbally) by Pharmacopeia or Bayer or its Affiliates
describing the scientific results of the Research Program to be published during
the Research Program or within one (1) year at the end of the Research Program
shall be subject to the prior review of the parties 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
any 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 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 10, the disclosing party agrees to remove such information from the
proposed publication or disclosure. Following the filing of any patent
application with 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 a invention claimed in such
patent application without the prior written consent of the other party.


                                      -35-

<PAGE>

                                   ARTICLE 11
                         REPRESENTATIONS AND WARRANTIES

     11.1  BAYER.  Bayer represents and warrants 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 of its obligations hereunder and (ii)
this Agreement is a legal and valid obligation binding upon it and enforceable
in accordance with its terms.

     11.2  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) it has the full right to enter into this
Agreement, and to fully perform 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
any intellectual property rights of third parties; and (viii) during the term of
the Research Program, Pharmacopeia will use reasonable efforts not to materially
breach the Columbia License.

     11.3  DISCLAIMER.  Bayer and Pharmacopeia specifically disclaim any
guarantee that the Research Program will be successful, in whole or in part. The
failure of the parties to successfully develop Agreement Compounds or Agreement
Products will not constitute a breach of any representation or warranty or other
obligation under this Agreement. Neither Bayer nor Pharmacopeia makes any
representation or warranty or guaranty that the Research Program will be
successful. 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, EXCLUDED TECHNOLOGY, BAYER TECHNOLOGY,
BAYER RANDOM LIBRARIES, FOCUSED LIBRARIES, AGREEMENT COMPOUNDS, OTHER COMPOUNDS,
INFORMATION DISCLOSED PURSUANT TO ARTICLE 10 OR AGREEMENT PRODUCTS 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.

                                      -36-

<PAGE>

                                   ARTICLE 12
                                 INDEMNIFICATION

     12.1  BAYER.  Bayer agrees to indemnify, defend and hold Pharmacopeia and
its Affiliates and their directors, officers, employees, agents and their
respective successors, heirs and assigns (the "Pharmacopeia Indemnities")
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 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) Bayer and its Affiliates
performance of the Research Program; 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.

     12.2  PHARMACOPEIA.  Pharmacopeia agrees to indemnify, defend and hold
Bayer, its Affiliates and Sublicensees and their respective directors, officers,
employees, agents and their respective 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 8.3 herein (including, without limitation, product liability claims),
(ii) the performance of the Research Program by Pharmacopeia; 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.

     12.3  PROCEDURE.  In the event that any Indemnitee intends to claim
indemnification under this Article 12 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 as 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 inappropriate 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

                                      -37-

<PAGE>

by this Article 12. 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 13
                              TERM AND TERMINATION

     13.1  TERM.  Except as set forth below, the term of this Agreement shall
begin as of the Effective Date, and shall continue in full force and effect on a
country-by-country and Agreement Product-by-Agreement Product basis unless
terminated as provided in this Article 13 until Bayer, its Affiliates and
Sublicensees have no remaining royalty payment obligations in a country, at
which time the Agreement shall expire in its entirety in such country.

     13.2  TERMINATION FOR BREACH.  Either party to this Agreement may terminate
this Agreement as to any 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) day; 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.

     13.3  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.

     13.4  TERMINATION DUE TO ACQUISITION.  During the Initial Term, if any 
third party which is a competitor of Bayer shall 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 transmitted to Pharmacopeia, its parent, successor, 
surviving or 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.

                                      -38-

<PAGE>

     13.5  EFFECT OF BREACH OR TERMINATION.

           13.5.1  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.

          13.5.2  RETURN  OF MATERIALS.  Upon any termination of this 
Agreement, Bayer and Pharmacopeia shall promptly return to the other 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).

          13.5.3  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 of this Agreement, inventory of the 
Agreement Product may be sold for up to six (6) months after date of 
termination, provided earned royalties are paid thereon.

          13.5.4  LICENSES.  The licenses granted Bayer herein shall 
terminate in the event of a termination by Pharmacopeia pursuant to Section 
13.2 or 13.3, and any licenses granted to Pharmacopeia under Section 8.3 
shall terminate in the event of a termination by Bayer pursuant to Section 
13.2, 13.3, or 13.4; provided, however, in the event of a termination by 
Bayer pursuant to Section 13.4, the licenses granted by Pharmacopeia shall 
remain in effect with respect to 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 or its Affiliates or Sublicensees hereunder 
and a breach entitling Pharmacopeia to terminate this Agreement relates 
solely to a single Agreement Product, then Pharmacopeia shall be entitled to 
terminate this Agreement only with respect to the applicable Agreement 
Product.

     13.6  SURVIVAL.  Articles 10, 11, 12, 13 and 14 of this Agreement, as 
well as Sections 2.7, 2.8, 2.9, 2.10, 4.1, 4.5, 5.3, 5.5, 5.7, 5.8, 7.1, 7.4, 
7.5, 8.3, 8.4, 8.5, 9.1, 9.2 and 9.4 shall survive the expiration or 
termination of this Agreement for any reason.

                                   ARTICLE 14
                                  MISCELLANEOUS

     14.1  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 the United Nations Convention on the
International Sale of Goods.

                                      -39-

<PAGE>

     14.2  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.

     14.3  WAIVER.  It is agreed that no waiver by either 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.

     14.4  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 Bayer guarantees the performance of such Affiliate(s) in a customary 
manner; except 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 any permitted assignee, and any such 
assignee shall agree to perform the obligations of the assignor.

     14.5  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 venturers of the others for any purpose as a result 
of this Agreement or the transactions contemplated thereby.

     14.6  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 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.

     14.7  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.

     14.8  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:

                                      -40-

<PAGE>

     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

     14.9  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.

     14.10  NO CONSEQUENTIAL DAMAGES.  In no event shall either 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.

     14.11  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 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.

     14.12  COMPLETE AGREEMENT.  This Agreement with its Exhibits, together with
the Random Library Agreement and Stock Purchase Agreement executed by the
parties of even

                                      -41-

<PAGE>

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.

     14.13  DISPUTE RESOLUTION.

            14.13.1  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 Section 14.13.2. 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

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.

            14.13.2  Any dispute or controversy arising out of or related to 
this Agreement which is not resolved pursuant to Section 14.13.1 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 14.1 hereof shall be applied to all 
matters in dispute between the parties with respect to this Agreement.

                                      -42-

<PAGE>

          14.13.3  Each party shall bear its own costs and attorneys' and
witness' fees. The costs of the administration of the arbitration proceeding,
including arbitrators' 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.

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

     14.15  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.

     14.16  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 the
Agreement.

     14.17  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.

     14.18  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.

                                      -43-

<PAGE>

     14.19  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. Mueller                   /s/ Joseph A. Mollica
    --------------------------------      ------------------------------------

Name:  Gerd D. Mueller                    Name:  Joseph A. Mollica
      ------------------------------            ------------------------------

Title:  Executive Vice President          Title:  Chairman and Chief Executive
       -----------------------------                Officer
                                                 -----------------------------


                                      -44-

<PAGE>

                                    EXHIBIT A

                                   RSC MEMBERS


For Bayer:  [ * * * ]






For Pharmacopeia:  [ * * * ]






[ * * *  Confidential Treatment Requested. ]

<PAGE>

                                    EXHIBIT B

                                BAYER AFFILIATES



                                    [ * * * ]





[ * * *  Confidential Treatment Requested. ]




<PAGE>


                                    EXHIBIT C




                               PHARMACOPEIA, INC.



              ---------------------------------------------------


                         COMMON STOCK PURCHASE AGREEMENT


              ---------------------------------------------------



<PAGE>

                                 TABLE OF CONTENTS

                                                                           PAGE
                                                                           ----

SECTION 1 - Authorization and Sale of Common Stock .......................   1

      1.1     Authorization of Common Stock ..............................   1
      1.2     Sale of Common .............................................   1

SECTION 2 - Closing Date; Delivery .......................................   1

      2.1     Closing Date ...............................................   1
      2.2     Delivery ...................................................   2

SECTION 3 - Representations and Warranties of the Company ................   2

      3.1     Organization and Standing; Articles and Bylaws .............   2
      3.2     Corporate Power ............................................   2
      3.3     Subsidiaries ...............................................   2
      3.4     Capitalization .............................................   2
      3.5     Authorization ..............................................   3
      3.6     Validity of Shares .........................................   3
      3.7     Title to Properties and Assets; Liens, etc. ................   3
      3.8     Material Contracts and Commitments .........................   3
      3.9     Patents, Trademarks, etc. ..................................   3
      3.10    Compliance with Other Instruments ..........................   4
      3.11    Litigation, etc. ...........................................   4
      3.12    Employees ..................................................   4
      3.13    Insurance ..................................................   5
      3.14    Registration Rights ........................................   5
      3.15    Governmental Consents, etc. ................................   5
      3.16    Offering ...................................................   5
      3.17    Disclosure .................................................   5
      3.18    Brokers or Finders .........................................   5
      3.19    Permits ....................................................   5
      3.20    Financial Statements .......................................   6
      3.21    Real Property Holding Corporation ..........................   6

SECTION 4 - Representations, Warranties and Covenants of the Purchaser ...   6

      4.1     Experience; Risk ...........................................   6
      4.2     Investment .................................................   7
      4.3     Restricted Securities; Rule 144 ............................   7
      4.4     Access to Data .............................................   7
      4.5     Authorization ..............................................   7
      4.6     Government Consents ........................................   7
      4.7     Further Limitations on Disposition .........................   8


                                         -i-

<PAGE>

                                TABLE OF CONTENTS
                                    (CONTINUED)


                                                                           PAGE
                                                                           ----

      4.8     Legends ....................................................   8
      4.9     Standstill .................................................   8
      4.10    Voting .....................................................   9

SECTION 5 - Conditions to Closing of Purchaser ...........................   9

      5.1     Representations and Warranties Correct .....................   9
      5.2     Covenants ..................................................   9
      5.3     Opinion of Company's Counsel ...............................  10
      5.4     Compliance Certificate .....................................  10
      5.5     Blue Sky ...................................................  10
      5.6     Stockholder Rights Agreement ...............................  10
      5.7     Research Agreement .........................................  10

SECTION 6 - Conditions to Closing of the Company .........................  10

      6.1     Representations ............................................  10
      6.2     Blue Sky ...................................................  10
      6.3     Stockholder Rights Agreement ...............................  10

SECTION 7 - Miscellaneous ................................................  11

      7.1     Governing Law ..............................................  11
      7.2     Survival ...................................................  11
      7.3     Successors and Assigns .....................................  11
      7.4     Entire Agreement; Amendment ................................  11
      7.5     Notices, etc. ..............................................  11
      7.6     Delays or Omissions ........................................  11
      7.7     Expenses ...................................................  12
      7.8     Counterparts ...............................................  12
      7.9     Severability ...............................................  12


Exhibits:

 A     -      Purchaser Schedule
 B     -      Schedule of Exceptions
 C     -      Amendment to Stockholder Rights Agreement
 D     -      Legal Opinion of Company Counsel


                                        -ii-

<PAGE>

                              PHARMACOPEIA, INC.

                        COMMON STOCK PURCHASE AGREEMENT


    This Agreement is made as of February 2, 1996, between Pharmacopeia, 
Inc., a Delaware corporation (the "Company"), and Bayer Corporation, an 
Indiana corporation, (the "Purchaser") in connection with the Collaboration 
Agreement (the "Research Agreement") between the Company and the Purchaser.


                                SECTION 1

                   AUTHORIZATION AND SALE OF COMMON STOCK


    1.1   AUTHORIZATION OF COMMON STOCK. The Company has authorized the sale 
and issuance of up to $10,000,000 of its Common Stock (the "Common"). The 
shares of the Common to be sold hereunder are collectively referred to as the 
"Shares."

    1.2   SALE OF COMMON. Subject to the terms and conditions hereof, on the 
Closing Date (as hereinafter defined) the Company will issue and sell to the 
Purchaser, and the Purchaser will purchase from the Company at a purchase 
price per share determined as set forth below, Shares of Common for a total 
of $10,000,000 as set forth in Section 2 below. The per share purchase price 
(the "Purchase Price") to be paid by the Purchaser for the Shares to be 
purchased from the Company on the Closing Date shall be based upon  [ * * * ] . 
The number of Shares to be issued to the Purchaser at the Closing shall be 
determined by dividing the $10,000,000 to be invested by the Purchaser at the 
Closing by the Purchase Price determined as set forth above and rounding up 
or down to the nearest whole share.


                                SECTION 2

                          CLOSING DATE; DELIVERY


    2.1 CLOSING DATE. The closing of the purchase and sale of the Common 
hereunder (the "Closing") shall be held at the offices of Wilson Sonsini 
Goodrich & Rosati, 650 Page Mill Road, Palo Alto, California 94304-1050 
("WSGR"). The closing of the sale of the Shares hereunder in exchange for

[ * * *  Confidential Treatment Requested. ]

<PAGE>

$10,000,000 from the Purchaser shall take place on February 2, 1996, or at 
such other time and place upon which the Company and the Purchaser shall 
agree (the date of the Closing is hereinafter referred to as the "Closing 
Date").

    2.2   DELIVERY. At or promptly following the Closing, the Company will 
deliver to Jones, Day, Reavis & Pogue, legal counsel to the Purchaser 
("Jones, Day"), a certificate or certificates representing the Shares to be 
purchased by the Purchaser at the Closing against payment of the purchase 
price therefor. Upon receipt by Jones, Day of the certificate representing 
the Shares, the Purchaser shall immediately tender the $10,000,000 purchase 
price for the Shares by wire transfer payable to the Company. Upon receipt of 
such funds by the Company, Jones, Day shall tender the certificate 
representing the Shares to the Purchaser.


                                   SECTION 3

                      REPRESENTATIONS AND WARRANTIES OF THE COMPANY


    Except as set forth on Exhibit B attached hereto, the Company hereby 
represents and warrants to the Purchaser as follows:

    3.1   ORGANIZATION AND STANDING; ARTICLES AND BYLAWS. The Company is a 
corporation duly organized and validly existing under, and by virtue of, the 
laws of the State of Delaware and is in good standing under such laws. The 
Company has all requisite corporate power to own and operate its properties 
and assets, and to carry on its business as presently conducted and as 
proposed to be conducted. The Company is qualified to do business as a 
foreign corporation in any jurisdiction in which failure to qualify would 
have a material adverse effect on the Company's business. The Company has 
furnished Purchaser true and complete copies of its Restated Certificate of 
Incorporation ("Restated Certificate") and Bylaws in effect as of the date 
hereof.

    3.2   CORPORATE POWER. The Company will have prior to the Closing Date 
all requisite legal and corporate power to execute and deliver this Agreement 
and the Amendment to Stockholder Rights Agreement in the form attached hereto 
as Exhibit C (the "Stockholder Rights Agreement"), to sell and issue the 
Shares hereunder and to carry out and perform its obligations under the terms 
of this Agreement and the transactions contemplated hereby.

    3.3   SUBSIDIARIES. The Company has no subsidiaries or affiliated 
companies and does not otherwise own or control any other corporation, 
association or business entity.

    3.4   CAPITALIZATION. The authorized capital stock of the Company 
consists of 40,000,000 shares of Common Stock, and 2,000,000 shares of 
Preferred Stock. 10,272,527 shares of Common Stock and no shares of Preferred 
Stock are issued and outstanding prior to the Closing. All such issued and 
outstanding shares have been duly authorized and validly issued, are fully 
paid and nonassessable, and have been issued in compliance with the 
applicable federal and state securities laws. The Company

                                      -2-
<PAGE>

has reserved 750,000 shares (net of repurchases) of its Common Stock for 
issuance to officers, employees, sales representatives and consultants of the 
Company pursuant to its 1994 Incentive Stock Plan, under which 379,400 shares 
of Common Stock have been issued and options exercisable for 363,575 shares 
of Common Stock are currently outstanding. The Company has also reserved a 
total of 150,000 shares of Common Stock for issuance under its 1995 Director 
Option Plan, none of which are issued, and 250,000 shares of Common Stock for 
issuance under its 1995 Employee Stock Purchase Plan, none of which are 
issued. Except as referenced herein, there are no options, warrants, 
conversion privileges or other rights presently outstanding to purchase or 
otherwise acquire any authorized but unissued shares of the capital stock or 
other securities of the Company, nor any agreements or understandings with 
respect thereto. Other than the Stockholder Rights Agreement, the Company is 
not a party or subject to any agreement or understanding, and, to the 
Company's knowledge, there is no agreement or understanding between any 
persons and/or entities, which affects or relates to the voting or giving of 
consents with respect to any security or by a director of the Company.

     3.5  AUTHORIZATION. All corporate action on the part of the Company, its 
officers, directors and shareholders necessary for the authorization, 
execution, delivery and performance of this Agreement and the Stockholder 
Rights Agreement by the Company, the authorization, sale, issuance and 
delivery of the Shares and the performance of the Company's obligations 
hereunder and thereunder has been taken or will be taken prior to the 
Closing. This Agreement and the Stockholder Rights Agreement, when executed 
and delivered by the Company, shall constitute the valid and binding 
obligations of the Company, enforceable against the Company in accordance 
with their respective terms, subject to laws of general application relating 
to bankruptcy, insolvency and the relief of debtors and rules of law 
governing specific performance, injunctive relief or other equitable 
remedies.

     3.6  VALIDITY OF SHARES. The Shares, when issued, sold and delivered in 
compliance with the provisions of this Agreement, will be duly and validly 
issued and will be fully paid and nonassessable and free and clear of all 
liens and encumbrances and restrictions on transfer other than as set forth 
in this Agreement and the Stockholder Rights Agreement, provided, however, 
that the Shares may be subject to restrictions on transfer under state and/or 
federal securities laws. Except as set forth herein or in the Stockholders 
Rights Agreement, there are no outstanding rights of first refusal or 
preemptive rights applicable to the Shares.

     3.7  TITLE TO PROPERTIES AND ASSETS; LIENS, ETC. The Company has good 
and marketable title to all its properties and assets, and is in compliance 
with the lease of all material properties leased by it, in each case subject 
to no mortgage, pledge, lien, lease, encumbrance or charge, other than the 
lien of current taxes not yet due and payable. The Company is not in default 
under or in breach of any provision of its leases, and the Company holds 
valid leasehold interests in the properties which it leases. The Company's 
material properties and assets are in good condition and repair, ordinary 
wear and tear excepted, in all material respects.

     3.8  MATERIAL CONTRACTS AND COMMITMENTS. Exhibit B sets forth a list of 
all agreements, contracts, indebtedness, liabilities, and other obligations 
to which the Company is a party or by which it or its assets are bound that 
(a) are material to the conduct and operations of its business and properties;


                                      -3-
<PAGE>

(b) involve in excess of $50,000 aggregating similar agreements or 
obligations to the same party; (c) involve to the Company's knowledge any of 
the officers, consultants, directors, employees, or shareholders of the 
Company or any members of the immediate family of the foregoing; or (d) 
obligate the Company to share, license, or develop any product. Copies of 
such agreements and contracts and documentation evidencing such liabilities 
and other obligations have been made available by the Company to the 
Purchaser.

     3.9  PATENTS, TRADEMARKS, ETC. To the knowledge of the Company, the 
Company has sufficient title and ownership of all patents, trademarks, service 
marks, trade names, copyrights, trade secrets, information, proprietary 
rights and processes necessary for its business as now conducted, and as 
proposed to be conducted, without conflict with or infringement of the rights 
of others. The Company has not received any communications alleging that the 
Company has violated or, by conducting its business as proposed, would 
violate, the proprietary or intellectual property rights of any other person 
or entity. The Company is not aware of any violation or infringement by a 
third party of any of the Company's patents, licenses, trademarks, service 
marks, trade names, copyrights, trade secrets or other proprietary rights.

     3.10  COMPLIANCE WITH OTHER INSTRUMENTS. The Company is not in violation 
of any term of its Restated Certificate or Bylaws, or in any material respect 
of any term or provision of any mortgage, indenture, contract, agreement, 
instrument, judgment or decree, and to its knowledge is not in violation of 
any order, statute, rule or regulation applicable to the Company. The 
execution, delivery and performance of and compliance with this Agreement and 
the Stockholder Rights Agreement and the issuance of the Shares have not 
resulted and will not result in any violation of, or conflict with, or 
constitute a default under any of the foregoing, or result in the creation of 
any mortgage, pledge, lien, encumbrance or charge upon any of the properties 
or assets of the Company; and there is no such violation or default which 
materially and adversely affects the business of the Company or any of its 
properties or assets.

     3.11  LITIGATION, ETC. There are no actions, suits, proceedings or 
investigations pending or, to the Company's knowledge, threatened against the 
Company or its properties before any court or governmental agency, which, 
either in any case or in the aggregate, might result in any material adverse 
change in the business, prospectus, financial condition, affairs, operations 
or equity ownership of the Company or any of its properties or assets, or in 
any material impairment of the right or ability of the Company to carry on 
its business as now conducted or as proposed to be conducted, or in any 
material liability on the part of the Company, and none which questions the 
validity of this Agreement or any action taken or to be taken in connection 
herewith. The Company is not a party or subject to the provisions of any 
order, judgment or decree issued by any court or governmental agency. There 
is no action, suit, proceeding, or investigation by the Company currently 
pending or that the Company intends to initiate.


                                      -4-
<PAGE>


     3.12  EMPLOYEES. To the Company's knowledge, no employee of the Company 
is or will be in violation of any judgment, decree or order of any court or 
administrative agency, or any term of any employment contract or any other 
contract (including without limitation any covenant not to compete) or 
agreement relating to the relationship of any such employee with the Company 
or any other party because of the nature of the business conducted or to be 
conducted by the Company or to the utilization by the employee of such 
employee's reasonable efforts with respect to such business. The Company does 
not have any collective bargaining agreements covering any of its employees. 
To the Company's knowledge, the Company is not using any inventions of any of 
its employees, consultants or officers made before their employment by the 
Company. To the Company's knowledge, no employee, consultant or officer has 
taken, removed, or made use of any proprietary documentation, manuals, 
products, materials, or any other tangible items from the employee's previous 
employers relating to the Company's business. All employees and officers of 
the Company with access to confidential or proprietary information or 
know-how of the Company have entered into agreements with the Company 
obligating them to hold such information in confidence and not to use such 
information for any purpose other than to benefit the Company.

     3.13  INSURANCE. The Company has in full force and effect fire, casualty 
and liability insurance policies with recognized insurers with such coverages 
as are sufficient in amount to allow replacement of the tangible properties 
of the Company that might be damaged or destroyed.

     3.14  REGISTRATION RIGHTS. Except as contemplated by the Stockholder 
Rights Agreement, the Company is not under any obligation to register any of 
its presently outstanding securities or any of its securities that may 
hereafter be issued.

     3.15  GOVERNMENTAL CONSENTS, ETC. No consent, approval, order or 
authorization of or designation, declaration or filing with any state or 
federal governmental authority on the part of the Company is required in 
connection with the valid execution and delivery of this Agreement, or the 
offer, sale or issuance of the Shares, or the consummation of any other 
transaction contemplated hereby, except qualification (or taking such action 
as may be necessary to secure an exemption from qualification, if available) 
under applicable Blue Sky laws, of the offer and sale of the Shares, which 
qualification, if required, will be accomplished in a timely manner prior to 
or promptly upon completion of the Closing.

     3.16  OFFERING. Based in part upon the accuracy of the Purchaser's 
representations in Section 4 hereof, the offer, sale and issuance of the 
Shares to be issued in conformity with the terms of this Agreement constitute 
transactions exempt from the registration requirements of Section 5 of the 
Securities Act of 1933, as amended (the "Securities Act").

     3.17  DISCLOSURE. No statement by the Company contained in this Agreement 
and the exhibits attached hereto, or in any certificate furnished or to be 
furnished to the Purchaser pursuant hereto, when taken as a whole, contains 
or will contain any untrue statement of a material fact or omits or will omit 
to state a material fact necessary in order to make the statements contained 
herein or therein not misleading in light of the circumstances under which 
they were made.



                                     -5-


<PAGE>

     3.18  BROKERS OR FINDERS. The Company has not incurred, and will not 
incur, directly or indirectly, any liability for brokerage or finders' fees 
or agents' commissions or any similar charges in connection with this 
Agreement or any transaction contemplated hereby.

     3.19  PERMITS. The Company has all franchises, permits, licenses, and 
any similar authority necessary for the conduct of its business as now being 
conducted, the lack of which could materially and adversely affect the 
business, properties, prospects, or financial condition of the Company, and 
the Company believes it can obtain, without undue burden or expense, any 
similar authority for the conduct of its business as planned to be conducted. 
The Company is not in default in any material respect under any of such 
franchises, permits, licenses, or other similar authority.

     3.20  FINANCIAL STATEMENTS. The Company has furnished to the Purchaser 
its audited balance sheet and statement of operations as of December 31, 1994 
and its unaudited balance sheet and statement of operations as of September 
30, 1995 (the "Financial Statements"). The Financial Statements are complete 
and correct in all material respects, are in accordance with the Company's 
books and records, and present fairly its financial condition as of that date 
and the results of its operations for the period indicated. Except as set 
forth in the Financial Statements, the Company does not have any material 
debts or liabilities, presently existing or contingent, other than debts or 
liabilities incurred in the ordinary course of business after September 30, 
1995.

     3.21  REAL PROPERTY HOLDING CORPORATION. The Company is not a "United 
States real property holding corporation," as that term is defined in 
Internal Revenue Code ("IRC") Section 897(c)(2) and Treasury Regulation 
Section 1.897-2(b). If at any time in the future the Company shall become a 
"United States real property holding corporation," the Company shall notify 
each foreign investor of such event as promptly as practicable. Within thirty 
(30) days after receipt of a request from a foreign investor, the Company 
shall prepare and deliver to such foreign investor the statement required 
under Treasury Regulation Section 1.897-2(h) and, subject to the succeeding 
sentence, either or both of the following documents: (i) an affidavit in 
conformance with the requirements of IRC Section 1445(b)(3) and the 
regulations thereunder or (ii) a notarized statement, executed by an officer 
having actual knowledge of the facts, that the shares of Company stock held 
by such foreign investor are of a class that is regularly traded on an 
established securities market, within the meaning of IRC Section 1445(b)(6) 
and the regulations thereunder. If the Company is unable to provide either of 
the documents described in (i) or (ii) above upon request, it shall promptly, 
and in any event within thirty (30) days, notify such foreign investor in 
writing of the reason for such inability. Finally, upon the request of a 
foreign investor and without regard to whether either document described in 
(i) or (ii) above has been requested, the Company shall reasonably cooperate 
with the efforts of such foreign investor to obtain a "qualifying statement" 
within the meaning of IRC Section 1445(b)(4) and the regulations thereunder 
or such other documents as would excuse a transferee of a foreign investor's 
interest from withholding of income tax imposed pursuant to IRC Section 
897(a).


                                SECTION 4



                                    -6-


<PAGE>

          REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE PURCHASER


     The Purchaser hereby represents, warrants and covenants to the Company 
with respect to the purchase of the Shares as follows:

     4.1  EXPERIENCE; RISK. The Purchaser has such knowledge and experience 
in financial and business matters that such Purchaser is capable of 
evaluating the merits and risks of the purchase of the Shares pursuant to 
this Agreement and of protecting the Purchaser's interests in connection 
therewith. The Purchaser is able to fend for itself in the transactions 
contemplated by this Agreement and has the ability to bear the economic risk 
of the investment, including complete loss of the investment. The Purchaser 
is experienced in evaluating and investing in new companies such as the 
Company.

     4.2  INVESTMENT. The Purchaser is acquiring the Shares for investment 
for its own account, not as a nominee or agent, and not with a view to, or 
for resale in connection with, any distribution thereof, and the Purchaser 
has no present intention of selling, granting any participation in, or 
otherwise distributing the same. The Purchaser understands that the Shares to 
be purchased have not been registered under the Securities Act by reason of a 
specific exemption from the registration provisions of the Securities Act 
which depends upon, among other things, the bona fide nature of the 
investment intent and the accuracy of such Purchaser's representations as 
expressed herein.

     4.3  RESTRICTED SECURITIES; RULE 144. The Purchaser understands that the 
Shares will be "restricted securities" under the federal securities laws 
inasmuch as they are being acquired from the Company in a transaction not 
involving a public offering and that under such laws and applicable 
regulations the Shares may be resold without registration under the 
Securities Act only in certain limited circumstances. The Purchaser 
acknowledges that the Shares must be held indefinitely unless subsequently 
registered under the Securities Act or an exemption from such registration is 
available. The Purchaser is aware of the provisions of Rule 144 promulgated 
under the Securities Act which permit limited resale of shares purchased in a 
private placement subject to the satisfaction of certain conditions, 
including, among other things, the existence of a public market for the 
shares, the availability of certain current public information about the 
Company, the resale occurring not less than two years after a party has 
purchased and paid for the security to be sold, the sale being effected 
through a "broker's transaction" or in transactions directly with a "market 
maker" (as provided by Rule 144(f)) and the number of shares being sold 
during any three-month period not exceeding specified limitations.

     4.4  ACCESS TO DATA. The Purchaser has had an opportunity to discuss the 
Company's business, management and financial affairs with the Company's 
management and the opportunity to review the Company's facilities and has 
received all information requested from the Company regarding the investment 
in the Company; PROVIDED, HOWEVER, that such opportunity and receipt shall not 
effect or otherwise diminish or obviate in any respect any of the 
representations and warranties of the Company under this Agreement.

     4.5  AUTHORIZATION. The Purchaser represents that it has the full right, 
power and authority to enter into and perform the Purchaser's obligations 
under this Agreement and the Stockholder Rights



                                     -7-


<PAGE>

Agreement, and this Agreement and the Stockholder Rights Agreement when 
executed and delivered by the Purchaser will constitute valid and binding 
obligations of the Purchaser, enforceable in accordance with their respective 
terms, subject to the laws of general application relating to bankruptcy, 
insolvency and the relief of debtors, rules of law governing specific 
performance, injunctive relief or other equitable remedies.

     4.6  GOVERNMENT CONSENTS. No consent, approval or authorization of or 
designation, declaration or filing with any state, federal, or foreign 
governmental authority on the part of the Purchaser is required in connection 
with the valid execution and delivery of this Agreement by the Purchaser, 
and the consummation by the Purchaser of the transactions contemplated hereby.

     4.7  FURTHER LIMITATIONS ON DISPOSITION. Without in any way limiting the 
representations set forth above, the Purchaser further agrees not to make any 
disposition of all or any portion of the Shares unless and until:

          (a)  There is then in effect a Registration Statement under the 
Securities Act covering such proposed disposition and such disposition is 
made in accordance with such Registration Statement; or

          (b)  The Purchaser shall have notified the Company of the proposed 
disposition and shall have furnished the Company with a statement of the 
proposed disposition, and if reasonably requested by the Company, such 
Purchaser shall have furnished the Company with an opinion of counsel, 
reasonably satisfactory to the Company, that such disposition will not 
require registration under the Act; PROVIDED, HOWEVER, that no such opinion 
of counsel shall be required for a transfer by a Purchaser that is a 
partnership to a partner of such Purchaser or a retired partner of such 
partnership who retires after the date hereof or the estate of any such 
partner or retired partner if the transferee agrees in writing to be bound 
by the terms of this Section 4.7.

     4.8  LEGENDS. It is understood that each certificate representing the 
Shares and any securities issued in respect thereof or exchange therefor 
shall bear legends in the following forms (in addition to any legend required 
under applicable state securities laws):

          "THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT 
          OF 1933. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR 
          HYPOTHECATED IN THE ABSENCE OF A REGISTRATION STATEMENT IN EFFECT 
          WITH RESPECT TO THE SECURITIES UNDER SUCH ACT OR AN OPINION OF 
          COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT 
          REQUIRED."

     4.9  STANDSTILL. The Purchaser agrees that for a period commencing on 
the date hereof and ending on the date which is ten (10) years from the date 
hereof, it shall not, except with the Company's prior written consent, 
acquire beneficial ownership of any additional securities of the Company in 
private transactions, or on the open market or otherwise authorize or make a 
tender, exchange or other offer



                                     -8-



<PAGE>

therefor without the written consent of the Company, if the effect of such 
acquisition would be to increase the percentage of the Total Potential Voting 
Power of Company represented by all Common Stock and other voting or 
non-voting securities convertible into Common Stock then owned by the 
Purchaser to 10.0% (or more) of the Total Potential Voting Power (as defined 
below) of the Company. For purposes hereof, Total Potential Voting Power 
shall mean the total number of votes which may be cast in the election of 
directors of the Company if all securities entitled to vote in the election 
of directors are present and voted and assuming that all then outstanding 
securities of the company that are convertible into, exchangeable for or 
otherwise exercisable to acquire shares of Common Stock are so converted, 
exchanged or otherwise exercised.


     For purposes of Section 4 hereof, the term "Purchaser" shall include, 
unless otherwise expressly set forth herein, the Purchaser and any entity 
controlling, controlled by or under common control with the Purchaser.

     4.10  VOTING. The Purchaser further agrees that, during the period that 
the standstill covenant set forth in Section 4.9 is in effect, the Purchaser 
will take such action as may be required so that all shares of Common Stock 
or other voting securities owned by the Purchaser are voted in favor of any 
action which has been approved by the Board of Directors and for which 
shareholder approval is required in connection with any future stock offering 
or financing, or any proposed acquisition of the Company. With regard to a 
proposed acquisition of the Company, the Purchaser agrees not to exercise any 
appraisal or similar statutory dissenters' rights with regard to such 
transaction, provided that such transaction has been approved by the 
Company's Board of Directors and by the holders of a majority of the 
Company's outstanding voting securities.



                                  SECTION 5

                      CONDITIONS TO CLOSING OF PURCHASER


     The Purchaser's obligation to purchase the Shares at the Closing is, at 
the option of the Purchaser, subject to the fulfillment on or prior to the 
Closing Date of the following conditions:

     5.1  REPRESENTATIONS AND WARRANTIES CORRECT. The representations and 
warranties made by the Company in Section 3 hereof shall be true and correct 
in all material respects when made, and shall be true and correct on the 
Closing Date in all material respects with the same force and effect as if 
they had been made on and as of said date.

     5.2  COVENANTS. All covenants, agreements and conditions contained in 
this Agreement to be performed by the Company on or prior to the Closing Date 
shall have been performed or complied with in all material respects.



                                     -9-


<PAGE>

     5.3  OPINION OF COMPANY'S COUNSEL. The Purchaser shall have received 
from Wilson Sonsini Goodrich & Rosati, P.C., counsel to the Company, an 
opinion addressed to the Purchaser, dated the Closing Date, substantially in 
the form of Exhibit D attached hereto.

     5.4  COMPLIANCE CERTIFICATE. The Company shall have delivered to the 
Purchaser a certificate executed by the Chief Executive Officer of the 
Company, dated the Closing Date and certifying to the fulfillment of the 
conditions specified in Sections 5.1 and 5.2 of this Agreement.

     5.5  BLUE SKY. The Company shall have obtained all necessary Blue Sky 
law permits and qualifications, or secured an exemption therefrom, required 
by any state for the offer and sale of the Shares.

     5.6  STOCKHOLDER RIGHTS AGREEMENT. The Company and the Purchaser shall 
have executed the Stockholder Rights Agreement.

     5.7  RESEARCH AGREEMENT. The Company and the Purchaser shall have 
executed the Research Agreement of even date herewith.



                                  SECTION 6

                    CONDITIONS TO CLOSING OF THE COMPANY


     The Company's obligation to sell and issue the Shares at the Closing is, 
at the option of the Company, subject to the fulfillment of the following 
conditions:

     6.1  REPRESENTATIONS. The representations made by the Purchaser in 
Section 4 hereof shall be true and correct in all material respects when 
made, and shall be true and correct on the Closing Date in all material 
respects with the same force and effect as if they had been made on and as of 
said date.

     6.2  BLUE SKY. The Company shall have obtained all necessary Blue Sky 
law permits and qualifications, or secured an exemption therefrom, required 
by any state for the offer and sale of the Shares.

     6.3  STOCKHOLDER RIGHTS AGREEMENT. The Purchaser shall have executed and 
delivered to the Company the Stockholder Rights Agreement.



                                    -10-

<PAGE>

                                    SECTION 7

                                  MISCELLANEOUS

    7.1   GOVERNING LAW. This Agreement shall be governed in all respects by 
the laws of the State of California as applied to contracts made and to be 
fully performed entirely within that state between residents of that state.

    7.2   SURVIVAL. The representations, warranties, covenants and agreements 
made herein shall survive any investigation made by any Purchaser and the 
closing of the transactions contemplated hereby.

    7.3   SUCCESSORS AND ASSIGNS. Except as otherwise provided herein, the 
provisions hereof shall inure to the benefit of, and be binding upon, the 
successors, assigns, heirs, executors and administrators of the parties 
hereto, provided, however, that the rights of the Purchaser to purchase the 
Shares shall not be assignable without the consent of the Company.

    7.4   ENTIRE AGREEMENT; AMENDMENT. This Agreement and the other documents 
delivered pursuant hereto constitute the full and entire understanding and 
agreement between the parties with regard to the subjects hereof and thereof. 
This Agreement or any term hereof may be amended, waived, discharged or 
terminated solely by a written instrument signed by the Company and the 
holders of a majority of the Shares.

    7.5   NOTICES, ETC. All notices and other communications required or 
permitted hereunder shall be in writing and shall be mailed by registered or 
certified mail, postage prepaid, or otherwise delivered by hand or by 
messenger, addressed (a) if to the Purchaser, at the address set forth on 
Exhibit A attached hereto or at such other address as shall have furnished to 
the Company upon not less than ten (10) days notice in writing, or (b) if to 
the Company, at the address of its principal office and addressed to the 
attention of the President and with a copy to Wilson Sonsini Goodrich & 
Rosati, 650 Page Mill Road, Palo Alto, California 94304-1050, Attention: 
Michael J. O'Donnell or at such other address as the Company shall have 
furnished to the Purchaser upon not less than ten (10) days notice in 
writing. Notwithstanding the above, any notice or communication to an address 
outside the United States shall additionally be given by telecopy and 
confirmed in writing sent by two (2) day guaranteed international courier.

    7.6   DELAYS OR OMISSIONS. No delay or omission to exercise any right, 
power or remedy accruing to any holder of any Shares, upon any breach or 
default of the Company under this Agreement, shall impair any such right, 
power or remedy of such holder nor shall it be construed to be a waiver of 
any such breach or default, or an acquiescence therein, or of or in any 
similar breach or default thereafter occurring; nor shall any waiver of any 
single breach or default be deemed a waiver of any other breach or default 
theretofore or thereafter occurring. Any waiver, permit, consent or approval 
of any kind or character on the part of any holder of any breach or default 
under this Agreement, or any waiver on the part of any holder of any 
provisions or conditions of this Agreement, must be in writing and shall be

                                     - 11 -

<PAGE>

effective only to the extent specifically set forth in such writing. All 
remedies, either under this Agreement or by law or otherwise afforded to any 
holder, shall be cumulative and not alternative.

    7.7   EXPENSES. Each party will pay its own costs and expenses in 
connection with the transactions contemplated hereby.

    7.8   COUNTERPARTS. This Agreement may be executed in any number of 
counterparts, each of which shall be enforceable against the parties actually 
executing such counterparts, and all of which together shall constitute one 
instrument.

    7.9   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 
without said provision.



                                     - 12 -

<PAGE>

    IN WITNESS WHEREOF, the parties have executed this Stock Purchase 
Agreement as of the day and date set forth above.




"COMPANY"                             PHARMACOPEIA, INC.,
                                      a Delaware corporation



                                      By:     /s/ illegible
                                          -------------------------------------

                                      Title: Chairman & Chief Executive Officer
                                            -----------------------------------



"PURCHASER"                           BAYER CORPORATION,
                                      an Indiana corporation



                                      By:   /s/ illegible
                                          -------------------------------------

                                      Title: Executive Vice President
                                            -----------------------------------




                                    -13-

<PAGE>


                                    EXHIBIT A

                                PURCHASER SCHEDULE



NAME AND ADDRESS OF PURCHASER


Bayer Corporation
400 Morgan Lane
West Haven, CT 06516
Attn: President, Pharmaceutical Division


<PAGE>


                                    EXHIBIT B

                              SCHEDULE OF EXCEPTIONS



    This Schedule of Exceptions, dated as of the Closing Date, is made and 
given pursuant to Section 3 of the Pharmacopeia, Inc. Common Stock Purchase 
Agreement dated as of February 2, 1996 (the "Agreement").

    The paragraph numbers in this Schedule of Exceptions correspond to the 
paragraph numbers in the Agreement; however, any information disclosed herein 
under any paragraph number shall be deemed to be disclosed and incorporated 
into any other paragraph number under the Agreement where such disclosure 
would be appropriate. Any terms defined in the Agreement shall have the same 
meaning when used in this Schedule of Exceptions as when used in the 
Agreement unless the context otherwise requires.

    3.4  CAPITALIZATION.

    The Company has issued two warrants each exercisable for 50,000 shares of 
Common Stock to Columbia University and Cold Springs Harbor Laboratory.

    3.8  MATERIAL CONTRACTS AND COMMITMENTS.

    The Company has entered into Consulting Agreements with the members of 
its Scientific Advisory Board and other consultants pursuant to which the 
Company is obligated to pay such individuals annual consulting fees ranging 
from $15,000 to $100,000.

    The Company has entered into employment letter agreements with the 
following employees: Joseph A. Mollica, John J. Baldwin, John C. Chabala, 
Nolan H. Sigal, and Lewis J. Shuster.

    The Company has entered into stock purchase agreements with certain of 
its employees, officers, directors, and consultants providing for vesting of 
the shares of Common Stock held by them. The Company has also signed stock 
option agreements with several employees and consultants.

    The Company has entered into a Financing and Common Stock Purchase 
Agreement with Avalon Medical Partners.

    The Company has entered into a Series A Preferred Stock Purchase 
Agreement, Series B Preferred Stock Purchase Agreement, Series C Preferred 
Stock Purchase Agreement, Series D Preferred Stock Purchase Agreement and 
Stockholder Rights Agreement with the holders of its Preferred Stock.

    The Company has entered into a Collaborative Agreement with Sandoz 
Corporation.


<PAGE>


    The Company has entered into a Collaboration Agreement and a Random 
Library Agreement with Schering-Plough, Ltd. and Schering Corporation.

    The Company has entered into a Collaboration Agreement with Berlex 
Laboratories, Inc.

    The Company has entered into a License Agreement with the National 
Institute of Health providing for the license of certain proprietary 
information to the Company.

    The Company has entered into a License Agreement with Columbia University 
and Cold Springs Harbor Laboratory providing for the license of certain 
proprietary information to the Company.

    The Company has entered into an equipment lease line in the amount of 
$1,350,000 with Lease Management Services, Inc., pursuant to which the 
Company will lease or finance equipment through loans secured by such 
equipment. In connection with such lease line the Company issued warrants 
which converted to Common Stock at the Company's Initial Public Offering (the 
"IPO").

    The Company has entered into an equipment lease line in the amount of 
$1,500,000 with Lease Management Services, Inc. pursuant to which the Company 
will lease or finance equipment through loans secured by such equipment.

    The Company has entered into a thirty (30) month facility lease for 
approximately 9,000 square feet at $2.77 per square foot per month, triple 
net.

    The Company has entered into a nine and one-half (9 1/2) month facility 
lease for approximately 9,934 square feet at $1.88 per square foot per month, 
triple net.

    The Company has entered into a leasing having a term of twenty-eight (28) 
months for approximately 10,000 square feet of office space at an annual rate 
of approximately $12.50 per square foot and 20,000 square feet of laboratory 
space at an annual rate of approximately $28.50 per square foot.

    The Company has entered into a ten (10) year facility lease for 
approximately 17,500 square feet at an average cost per square foot of $26.54, 
triple net.

    The Company has entered into a Materials Transfer Agreement with Bunsen 
Rush Laboratories.

    The Company entered into a Non-Exclusive License Agreement with 
Washington University.



                                    -2-


<PAGE>


    The Company has outstanding, in the ordinary course of business, various 
open purchase orders for equipment, supplies, services, and leasehold 
improvements. Several of these may exceed $25,000.

    The Company has entered into various software license agreements with MDL 
Information Systems, Inc., Molecular Simulations and others.

    The Company has entered into Chemical Synthesis Agreements with KRS 
Consultants, Inc. and Tyger Scientific.

    The Company has entered into a Product Development Consortium Agreement 
with Argonaut Technologies, Inc. for the development of instruments that will 
facilitate the development and implementation of solid phase synthetic 
organic chemistry.

    3.19 PERMITS.

    The Company believes it may be required to obtain one or more permits 
from the county in connection with its proposed new facility lease and 
possible changes to its current facilities. The Company is in the process of 
obtaining such permits.

    3.20 BUSINESS PLAN.

    The Company has not prepared a current version of its Business Plan in 
connection with the sale of the Shares and therefore no Business Plan has 
been provided to the Purchaser. The Company has provided the Purchaser with a 
copy of the Prospectus prepared in connection with the Company's IPO.




                                     -3-

<PAGE>


                                   EXHIBIT C

                                   AMENDMENT



    This Amendment is made effective as of February 2, 1996 between 
Pharmacopeia, Inc. (the "Company"), the undersigned holders ("Stockholders") 
of Common Stock of the Company listed on Exhibit A who are parties to, or 
have been assigned rights under, the Company's Stockholder Rights Agreement 
dated February 15, 1995 (the "Rights Agreement") and Bayer Corporation (the 
"New Investor") with regard to the issuance by the Company of shares of the 
Company's Common stock (the "Shares") in exchange for an investment of 
$10,000,000 from the New Investor. The Rights Agreement is attached hereto as 
Exhibit 1 and incorporated herein by reference. The Company and the 
Stockholders agree as follows:

    1.  The Stockholders hereby consent to the inclusion of (i) the New 
Investor as a party to the Rights Agreement and (ii) the Shares of Common 
Stock being issued to the New Investor as "Registrable Securities" as 
defined in Section 1.8 of the Rights Agreement. The Rights Agreement is 
hereby amended to include the New Investor as a "Holder" thereunder and to 
include the Shares in the definition of Registrable Securities thereunder. 
By execution of this Amendment the New Investor shall become a party to the 
Rights Agreement and shall be entitled to all of the rights and subject to all
of the obligations of a Holder thereunder.

    2.  The Company, the Stockholders and the New Investor acknowledge and 
agree that the provisions of Section 2 and Section 3 of the Rights Agreement 
have terminated (except as otherwise specifically provided in Section 3.2) 
and are no longer of any force and effect as a result of the Company closing 
the IPO as set forth in Sections 2.3 and 3.2 of the Rights Agreement.

    3.  This Amendment shall be effective with regard to all Stockholders 
upon execution by the Company and the Stockholders who hold more than fifty 
percent (50%) of the outstanding Registrable Securities as provided in 
Section 6.2 of the Rights Agreement. This Amendment may be executed in one or 
more counterparts, each of which shall be deemed an original, and all of 
which together shall constitute one instrument.




THE COMPANY:


                                 PHARMACOPEIA, INC.



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------


<PAGE>


HOLDERS:                         ABINGWORTH BIOVENTURES



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------



                                 AVALON BIOVENTURES, L.P.



                                 By:
                                    -------------------------------------------
                                    General Partner



                                 AVALON MEDICAL PARTNERS, L.P.



                                 By:
                                    -------------------------------------------
                                    General Partner



                                 ----------------------------------------------
                                 David Baer, Custodian for Adam D. Sigal under
                                 the New Jersey Uniform Transfers Act until he
                                 attains age 21



                                 ----------------------------------------------
                                 David Baer, Custodian for Joshua I. Sigal under
                                 the New Jersey Uniform Transfers Act until he
                                 attains age 21



                                 ----------------------------------------------
                                 David Baer, Custodian for Yaron M. Sigal under
                                 the New Jersey Uniform Transfers Act until he
                                 attains age 21



                                 ----------------------------------------------
                                 Howard Birndorf



                                 ----------------------------------------------
                                 Jonathan Burbaum


                                     -2-

<PAGE>




                                 ----------------------------------------------
                                 Robert A. Curtis



                                 FRIENDS OF AVALON VENTURES



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------



                                 GREYLOCK EQUITY LIMITED
                                 PARTNERSHIP



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------



                                 INSTITUTIONAL VENTURE MANAGEMENT V



                                 By:
                                    -------------------------------------------
                                    General Partner



                                 INSTITUTIONAL VENTURE PARTNERS V
                                 By:     Institutional Venture Management V,
                                         its General Partner



                                 By:
                                    -------------------------------------------
                                    General Partner



                                 KLEINER PERKINS CAUFIELD & BYERS VI
                                 By:     Kleiner Perkins Caufield & Byers VI
                                         Associates



                                 By:
                                    -------------------------------------------
                                    General Partner


                                   -3-


<PAGE>


                                 KLEINER PERKINS CAUFIELD & BYERS VI
                                 FOUNDERS FUND
                                 By:     Kleiner Perkins Caufield & Byers VI
                                         Associates



                                 By:
                                    -------------------------------------------
                                    General Partner



                                 OAK INVESTMENT PARTNERS V, LIMITED 
                                 PARTNERSHIP
                                 By:     Oak Associates V, Limited Partnership,
                                         as General Partner



                                 By:
                                    -------------------------------------------
                                    a General Partner



                                 OAK V AFFILIATES FUND, LIMITED
                                 PARTNERSHIP
                                 By:     Oak V Affiliates, Limited Partnership,
                                         as General Partner



                                 By:
                                    -------------------------------------------



                                 SCHERING CORPORATION



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------



                                 SCHERING BERLIN VENTURE
                                 CORPORATION



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------


                                       -4-


<PAGE>




                                 ----------------------------------------------
                                 Nolan H. Sigal



                                 STANFORD UNIVERSITY



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------



                                 ----------------------------------------------
                                 Robert S. Thorpe



                                 VECTOR LATER-STAGE EQUITY FUND, L.P.
                                 By:     Vector Fund Management L.P.
                                 Its:    General Partner


                                 By:     Vector Asset Management, Inc.
                                 Its:    General Partner



                                         By:
                                            -----------------------------------

                                         Its:
                                             ----------------------------------


                                   -5-


<PAGE>


By execution of this Amendment the undersigned holder of shares of Common 
Stock of Pharmacopeia, Inc. (the "Company") agrees to become a party to the 
Company's Stockholder Rights Agreement as a "Holder" thereunder as set forth 
in this Amendment.



                                 BAYER CORPORATION



                                 By:
                                    -------------------------------------------

                                 Title:
                                       ----------------------------------------


                                    -6-



<PAGE>

                                   EXHIBIT A
                                   ---------

                            SCHEDULE OF STOCKHOLDERS


          Name and Address of Stockholder
- - ----------------------------------------------

Avalon Bioventures
1020 Prospect Street, Suite 405
La Jolla, CA 92037
Attn: Lawrence A. Bock

Avalon Medical Partners
1020 Prospect Street, Suite 405
La Jolla, CA 92037
Attn: Lawrence A. Bock

Howard Birndorf
Nanogen Incorporated
11588 Sorrento Valley Road, #16
San Diego, CA 92121

Institutional Venture Partners V, L.P.
3000 Sand Hill Road, 2-290
Menlo Park, CA 94025
Attn: Samuel Colella

Institutional Venture Management V
3000 Sand Hill Road, 2-290
Menlo Park, CA 94025
Attn: Samuel Colella

Kleiner Perkins Caufield & Byers VI, L.P.
2750 Sand Hill Road
Menlo Park, CA 94025
Attn: Brook Byers

KPCB VI Founders Fund, L.P.
2750 Sand Hill Road
Menlo Park, CA 94025
Attn: Brook Byers

Oak Investment Partners V, Limited Partnership
One Gorham Island
Westport, CT 06880
Attn: Eileen M. More


                                      -7-
<PAGE>

Oak V Affiliates Fund, Limited Partnership
One Gorham Island
Westport, CT 06880
Attn: Eileen M. More

Vector Later-Stage Equity Fund, L.P.
1751 Lake Cook Road, Suite 350
Deerfield, IL 60015
Attn: Linda Ginsburg

Greylock Equity Limited Partnership
One Federal Street
Boston, MA 02110-2065
Attn: William W. Helman

Abingworth Bioventures
c/o Buchalter, Nemer, Fields & Younger
601 S. Figueroa, Suite 2400
Los Angeles, CA 90017-5704

Robert Curtis
238 Bullock Drive
Princeton, NJ 08540

Jonathan Burbaum
415 Linden Avenue
Westfield, NJ 07090

David Baer, Custodian for Adam D. Sigal under
 the New Jersey Uniform Transfers Act until he
 attains age 21
1446 Graymill Drive
Westfield, NJ 07090

David Baer, Custodian for Joshua I. Sigal under
 the New Jersey Uniform Transfers Act until he
 attains age 21
1446 Graymill Drive
Westfield, NJ 07090

David Baer, Custodian for Yaron M. Sigal under
 the New Jersey Uniform Transfers Act until he
 attains age 21
1446 Graymill Drive
Westfield, NJ 07090


                                      -8-
<PAGE>

Nolan H. Sigal
Pharmacopeia, Inc.
101 College Road East
Princeton, NJ 07090

Robert S. Thorpe
Financial Resources Group
750 Bay Street, Suite 3
San Francisco, CA 94109

Friends of Avalon Ventures
1020 Prospect Street, Suite 405
La Jolla, CA 92037
Attn: Lawrence A. Bock

Stanford University
2770 Sand Hill Road
Menlo Park, CA 94025
Attn: Carol Gilmer

Schering Corporation
200 Galloping Hill Road
Kenilworth, NJ 07033

Schering Berlin Venture Corporation
Berlex Laboratories
110 East Hanover Avenue
Cedar Knolls, NJ 07927
Attn: John Nicolson


















                                      -9-



<PAGE>


                                    EXHIBIT D







                                 February 2, 1996


TO THE PURCHASER LISTED
IN EXHIBIT A TO THE
PHARMACOPEIA, INC.
COMMON STOCK PURCHASE AGREEMENT
DATED FEBRUARY 2, 1996



Ladies and Gentlemen:

    Reference is made to the Common Stock Purchase Agreement, complete with 
all listed exhibits thereto, dated as of February 2, 1996 (the "Agreement"), 
by and among Pharmacopeia, Inc., a Delaware corporation (the "Company"), and 
the Purchaser, which provides for the sale and issuance by the Company to the 
Purchaser of shares of Common Stock (the "Shares") of the Company. This 
opinion is rendered to you pursuant to Section 5.3 of the Agreement, and all 
terms used herein have the meanings defined for them in the Agreement unless 
otherwise defined herein.

    We have acted as counsel for the Company in connection with the 
negotiation of the Agreement and the issuance of the Shares. As such counsel, 
we have made such legal and factual examinations and inquiries as we have 
deemed advisable or necessary for the purpose of rendering this opinion. In 
addition, we have examined originals or copies of corporate records of the 
Company, certificates of public officials and such other documents and 
questions of law that we consider necessary or advisable for the purpose of 
rendering this opinion. In such examination, we have assumed the genuineness 
of all signatures on original documents, the authenticity of all documents 
submitted to us as originals, the conformity to original documents of all 
copies submitted to us as copies thereof, the legal capacity of natural 
persons, and the due execution and delivery of all documents (except as to 
due execution and delivery by the Company) where due execution and delivery 
are a prerequisite to the effectiveness thereof.


<PAGE>


    As used in this opinion, the expression "to our knowledge" with reference 
to matters of fact means that, after an examination of documents made 
available to us by the Company, and after inquiries of officers of the 
Company, but without any further independent factual investigation, we find 
no reason to believe that the opinions expressed herein are factually 
incorrect. Further, the expression "to our knowledge" with reference to 
matters of fact refers to the current actual knowledge of the attorneys of 
this firm who have worked on matters for the Company solely in connection 
with the Agreement and the transactions contemplated thereby. Except to the 
extent expressly set forth herein or as we otherwise believe to be necessary 
to our opinion, we have not undertaken any independent investigation to 
determine the existence or absence of any fact, and no inference as to our 
knowledge of the existence or absence of any fact should be drawn from our 
representation of the Company or the rendering of the opinion set forth below.

    For purposes of this opinion, we are assuming that you have all requisite 
power and authority, and have taken any and all necessary corporate or 
partnership action, to execute and deliver the Agreement, and we are assuming 
that the representations and warranties made by you in the Agreement are true 
and correct. We are also assuming that you have purchased the Shares for 
value, in good faith and without notice of any adverse claims within the 
meaning of the California Uniform Commercial Code.

    The opinions hereinafter expressed are subject to the following 
qualifications:

         (a)  We express no opinion as to the effect of applicable 
bankruptcy, insolvency, reorganization, moratorium or other similar federal 
or state laws affecting the rights of creditors;

         (b)  We express no opinion as to the effect or availability of rules 
of law governing specific performance, injunctive relief or other equitable 
remedies (regardless of whether any such remedy is considered in a proceeding 
at law or in equity);

         (c)  We express no opinion as to compliance with applicable 
anti-fraud provisions of federal or state securities laws;

         (d)  We express no opinion as to the enforceability of the 
indemnification provisions of Section 4.7 of the Stockholder Rights 
Agreement, to the extent such provisions may be subject to limitations of 
public policy and the effect of applicable statutes and judicial decisions;

         (e)  We are members of the Bar of the State of California, and we 
are not expressing any opinion as to any matter relating to the laws of any 
jurisdiction other than the federal laws of the United States of America, the 
General Corporation Law of Delaware and the laws of the State of California. 
To the extent this opinion addresses applicable securities laws of states 
other than the State of California, we have not retained nor relied on the 
opinion of counsel admitted to the bar of such states, but rather have relied 
on compilations of the securities laws of such states contained in reporting 
services presently available to us.


                                        -2-


<PAGE>


    Based upon and subject to the foregoing, and except as disclosed in the 
Agreement or in the Schedule of Exceptions thereto, we are of the opinion 
that:

    1.  The Company is a corporation duly organized and validly existing 
under, and by virtue of, the laws of the State of Delaware and is in good 
standing under such laws. The Company has requisite corporate power to own 
and operate its properties and assets, and to carry on its business as 
currently conducted.

    2.  The Company has all requisite legal and corporate power to execute 
and deliver the Agreement and the Stockholder Rights Agreement, to sell and 
issue the Shares under the Agreement, and to carry out and perform its 
obligations under the terms of the Agreement.

    3.  The authorized capital stock of the Company consists of 
40,000,000 shares of Common Stock and 2,000,000 shares of Preferred Stock. 
Immediately prior to the Closing there were issued and outstanding 
10,272,527 shares of Common Stock and no shares of Preferred Stock. All such 
issued and outstanding shares have been duly authorized, validly issued and 
are fully paid and nonassessable. The Company has reserved 1,150,000 shares 
of Common Stock for issuance to officers, directors, employees, sales 
representatives and consultants of the Company pursuant to its Incentive 
Stock Plans. To our knowledge, except as set forth in the Agreement or the 
Schedule of Exceptions thereto, there are no other preemptive rights, 
warrants or conversion privileges or other rights (or agreements for any such 
rights) outstanding to purchase or otherwise obtain any of the Company's 
securities.

    4.  The Shares, when issued, sold and delivered in accordance with the 
terms of the Agreement, will be duly and validly issued, fully paid and 
nonassessable and will be free and clear of any liens or encumbrances, other 
than those imposed by holders thereof. However, the Shares may be subject to 
restrictions on transfer under state and federal securities laws.

    5.  All corporate actions on the part of the Company and its directors 
and stockholders that are necessary for the authorization, execution, 
delivery and performance of the Agreement and the Stockholder Rights 
Agreement by the Company, the authorization, sale, issuance and delivery of 
the Shares, and the performance of the Company's obligations under the 
Agreement and the Stockholder Rights Agreement have been taken. The Agreement 
and the Stockholder Rights Agreement have been duly and validly executed and 
delivered by the Company, and constitute valid and binding obligations of the 
Company, enforceable against the Company in accordance with their respective 
terms.

    6.  The execution, delivery and performance of and compliance with the 
terms of the Agreement and the Stockholder Rights Agreement, and the issuance 
of the Shares, do not violate any provision of the Company's Restated 
Certificate of Incorporation, as amended, or Bylaws, as amended. To our 
knowledge, the execution, delivery and performance of and compliance with the 
Agreement and the Stockholder Rights Agreement, and the issuance of the 
Shares have not resulted and will not result in any violation of, or conflict 
with, or constitute a default under, any material

                                   -3-


<PAGE>

contract, agreement, instrument, judgment or decree binding upon the Company 
or any applicable federal, state or local law, rule or regulation in any 
respect.

    7.  To our knowledge, there are no actions, suits, proceedings or 
investigations pending against the Company or its properties before any court 
or governmental agency (nor, to our knowledge, is there any written threat 
thereof), which, if adversely determined, might result in any material 
adverse change in the business or financial condition of the Company or which 
questions the validity of the Agreement or any action taken or to be taken by 
the Company in connection therewith.

    8.  No consent, approval, order or authorization of, or registration, 
qualification, designation, declaration or filing with, any federal, state or 
local governmental authority on the part of the Company is required in 
connection with the offer, sale or issuance of the Shares or the consummation 
of any other transaction contemplated thereby, except for (and subject to) 
the qualification (or taking such action as may be necessary to secure an 
exemption from qualification, if available) under applicable "blue sky" laws 
of the offer and sale of the Shares.

    9.  Subject to the accuracy of your representations set forth in 
Section 4 of the Agreement, the offer, sale and issuance of the Shares to you 
in conformity with the terms of the Agreement are exempt from the 
registration requirements of Section 5 of the Securities Act of 1933, as 
amended.

    This opinion is furnished to you solely for your benefit in connection 
with the purchase of the Shares and may not be relied upon by any other 
person or for any other purposes without prior written consent.


                                 Very truly yours,




                                 WILSON, SONSINI, GOODRICH & ROSATI
                                 Professional Corporation


                                    -4-




<PAGE>

                           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

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                                  -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

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                                  -11-


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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

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                                  -12-


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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

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                                   -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.

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                                     -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 

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                                     -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.

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                                     -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. ]





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