TECHNOLOGY ACQUISITION AGREEMENT

This TECHNOLOGY ACQUISITION AGREEMENT is entered into as of June 15, 1999 by and
between  PFIZER INC, a Delaware  corporation,  having an office at 235 East 42nd
Street,  New York,  New York 10017 and its Affiliates  ("Pfizer"),  and NEUROGEN
CORPORATION, a Delaware corporation, having an office at 35 Northeast Industrial
Road, Branford, Connecticut 06405 and its Affiliates ("Neurogen").

WHEREAS,  Neurogen has developed a technology  known as Accelerated  Intelligent
Drug Design ("AIDD") which integrates biological assays,  chemical synthesis and
computational analysis and is generally useful in pharmaceutical drug discovery;

WHEREAS,  Pfizer  seeks to  collaborate  with  Neurogen on the  transfer of AIDD
technology to Pfizer and further development of AIDD technology;

WHEREAS,  Pfizer  seeks to obtain a  nonexclusive  license to trade  secrets and
copyrights to AIDD technology,  including the technology described in Exhibit A,
which is attached to and made a part of this Agreement; and

WHEREAS,  Neurogen  is  willing to enter into a  technology  collaboration  with
Pfizer to transfer AIDD technology, to grant such license and to further develop
AIDD technology.

NOW, THEREFORE, the parties agree as follows:

1.    Definitions

Whenever used in this Agreement,  the terms defined in this Section 1 shall have
the meanings specified.

     1.1 "Acceptance Testing"

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     1.2 "Affiliate"  means any corporation or other legal entity  "controlled,"
"controlling,"  or "under common  control  with,"  another  corporation or legal
entity,  where  "control"  means  ownership,  directly or  indirectly,  of fifty
percent (50%) or more of the voting capital shares or similar voting  securities
of the other entity.

     1.3 "AIDD Software" means existing computer programs  developed by Neurogen
for use in System, and Improvements to it.

     1.4  "AIDD  Unit"  means  an  assembled  unit  of  Components  in a  single
operational System unit as further described,  attached to and made part of this
Agreement as Exhibit C.

     1.5 "CAN" means the  Pfizer-documented  event within a Program in which, in
Pfizer's sole unfettered discretion, a Compound is recognized as a candidate for
drug development.

     1.6  "Collaboration  Plan"  means the written  plan  adopted by the parties
prior to the execution of this  Agreement and amended from time to time, by both
parties,  to  describe  activities  to be carried  out by them  pursuant to this
Agreement.  The initial  Collaboration Plan is attached to and made part of this
Agreement as Exhibit D.

     1.7  "Collaboration  Program" means the technology  transfer and technology
development program contemplated in this Agreement to be conducted by Pfizer and
Neurogen pursuant to the Collaboration Plan.

     1.8 "Components" mean the equipment  described in Exhibit C forming an AIDD
Unit.
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     1.9  "Compound"  means  an  active  compound  whose  chemical  lineage  and
structure;  (a) can,  by using the  Tracking  System,  be  traced to a  specific
Program;  and (b) falls within a claim in a pending patent application or issued
patent owned by or licensed to Pfizer.

     1.10 "Contract Period" means the period beginning on the Effective Date and
ending on the date on which this Agreement terminates.

     1.11 "Effective Date" means June 15, 1999.

     1.12  "Islands"  means the set of algorithms  developed by Neurogen  which;

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     1.13 "Neurogen  Confidential  Information"  means all information about any
element of the Neurogen  Technology which is disclosed by Neurogen to Pfizer and
designated  "Confidential"  in writing by Neurogen at the time of  disclosure to
Pfizer or within thirty (30) days  following  disclosure to the extent that such
information  is not (i) known to Pfizer as of the date of  disclosure  to Pfizer
other than by virtue of a prior  confidential  disclosure to Pfizer by Neurogen;
or (ii) disclosed in published  literature,  or otherwise generally known to the
public  through no fault or omission of Pfizer;  or (iii)  obtained from a third
party free from any obligation of confidentiality to Neurogen.

     1.14  "Neurogen  Technology"

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     1.15 "Improvements"

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     1.16  "Patent  Rights and  Copyrights"  shall  mean all  patent  rights and
copyrights  in  and  to  inventions   and   individual   works  of   authorship,
respectively,  within Neurogen Technology or Pfizer Technology  including issued
patents and pending patent applications  whether domestic or foreign,  including
all substitutions, continuations, continuations-in-part, divisions and renewals,
and letters  patent  granted  thereon,  and all  reissues,  re-examinations  and
extensions thereof.

     1.17 "Pfizer  Confidential  Information"

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     1.18 "Pfizer Technology" means Pfizer technology developed by or for Pfizer
alone or jointly with third parties (other than Neurogen) prior to the Effective
Date or during the  Contract  Period,  including  but not limited to  biological
data, computational chemistry software, ADME-toxicity technology, analytical and
synthetic chemistry protocols,  chemical fragments, and HTS and uHTS methods for
chemistry and screening.

     1.19  "Program"
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     1.20 "Project II"
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     1.21 "Sites"
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     1.22 "System"
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     1.23 "Tracking  System"

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 2.       Collaboration Program

     2.1 Purpose.  Neurogen and Pfizer shall conduct the  Collaboration  Program
throughout the Contract Period. The objectives of the Collaboration  Program are

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     2.2  Collaboration  Plan. The initial  Collaboration  Plan is described in,
attached to and made part of this Agreement as Exhibit D. The Steering Committee
shall prepare an amended  Collaboration  Plan no later than at least ninety (90)
days  prior  to  each   anniversary  of  the  Effective   Date,   which  amended
Collaboration Plan will apply to the next year. Each amended  Collaboration Plan
shall be appended to Exhibit D and made part of this Agreement.

     2.3 Steering Committee

          2.3.1  Purpose.   Pfizer  and  Neurogen  shall  establish  a  Steering
     Committee (the "Steering Committee"):
               (a) to review and evaluate progress under the Collaboration Plan;
               (b) to prepare the Collaboration Plan and any amendments;
               (c) to prepare and evaluate progress on Project II plans;
               (d) to coordinate visits and training; and
               (e) to  coordinate  and   monitor  exchange  of  information  and
                   materials  that relate to the  Collaboration  Program.  (This
                   function  shall survive the termination of this Agreement).

          2.3.2 Membership. Pfizer and Neurogen each shall appoint, in it's sole
     unfettered  discretion,   four  (4)  members  to  the  Steering  Committee.
     Substitutes may be appointed at any time by a party by notice in writing to
     the other party; provided, however,

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          The members initially shall be:
          Pfizer Appointees:

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          Neurogen Appointees:

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          2.3.3  Chair.   The  Steering   Committee  shall  be  chaired  by  two
     co-chairpersons, one appointed by each of the parties.

          2.3.4  Meetings.  The Steering  Committee shall meet at least four (4)
     times per year, at places and on dates  selected by each party in turn. One
     (1) of the four (4) meetings may be by videoconference.  Representatives of
     Pfizer  or  Neurogen  or both,  in  addition  to  members  of the  Steering
     Committee, may attend such meetings at the invitation of either party.

          2.3.5 Minutes.  The Steering  Committee shall keep accurate minutes of
     its  deliberations,  which  record all proposed  decisions  and all actions
     recommended  or taken.  Drafts of the  minutes  shall be  delivered  to all
     Steering  Committee  members  within  ten (10)  business  days  after  each
     meeting.  The  party  hosting  the  meeting  shall be  responsible  for the
     preparation  and  circulation of the draft minutes.  Draft minutes shall be
     edited by the  co-chairpersons  and shall be issued in final form only with
     their approval and agreement.

          2.3.6 Decisions.

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          2.3.7  Expenses.  Pfizer and Neurogen  shall each bear all expenses of
     their  respective  members related to their  participation  on the Steering
     Committee.

          2.4 Reports and Materials.

               2.4.1 Reports. During the Contract Period, Neurogen shall furnish
          to the Steering Committee:

                    (a) summary  written  reports  describing its progress under
               the Collaboration Plan and delivered electronically within thirty
               (30) days after the end of each three (3) month  period and seven
               (7) days prior to the Steering Committee  meeting,  commencing on
               the Effective Date; and

                    (b)  comprehensive  written  reports within thirty (30) days
               after the end of each  contract  year,  describing  in detail the
               work accomplished by it under the Collaboration  Plans during the
               year and discussing and evaluating the results of such work.

               2.4.2  Materials.  During the Contract Period Neurogen and Pfizer
          shall as a matter of course, as described in the  Collaboration  Plan,
          or upon each other's  written or oral  request,  furnish to each other
          samples of biochemical or synthetic chemical materials,  which are (a)
          part of Pfizer  Technology or Neurogen  Technology;  and (b) necessary
          for  each   party  to  carry  out  its   responsibilities   under  the
          Collaboration  Plan.  To the extent that the  quantities  of materials
          requested  by either  party  exceed  the  quantities  set forth in the
          Collaboration  Plan,  the requesting  party shall  reimburse the other
          party  for  the  reasonable  costs  of  such  materials  if  they  are
          furnished.

          2.5 Notebooks and Personnel. Neurogen shall provide suitable personnel
     for the  work to be done by  Neurogen  in  carrying  out the  Collaboration
     Program.  All work performed by Neurogen staff under the Collaboration Plan
     with respect to Project II  Improvements  and  Acceptance  Testing shall be
     recorded in laboratory, notebooks, which Pfizer may review, extract or copy
     at any time, upon reasonable notice.

          2.6 Neurogen's Activities:  During the Contract Period, Neurogen shall
     perform the following technology transfer and development  activities under
     the Collaboration Program.

               2.6.1 Neurogen shall transfer

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               The Steering  Committee  will organize and monitor these transfer
          activities which shall include without limitation:

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          If Pfizer requests additional training visits by Neurogen staff to any
          Site, and such visits do not coincide with Steering Committee meetings
          at such Site, then Pfizer shall reimburse  Neurogen for its reasonable
          staff travel expenses for such visit.

               2.6.2  Neurogen  shall   construct  the  Systems  and  Components

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          shall perform Acceptance Testing on each AIDD Unit; and shall deliver

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          as  set  forth  in  the  production  and  delivery   schedule  in  the
          Collaboration Plan;  provided,  however,  that Neurogen shall have the
          right, upon thirty (30) days written notice to Pfizer, to deliver

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          to Pfizer prior to their respective scheduled delivery dates. Neurogen
          and Pfizer will perform Acceptance Testing on its premises

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          The location of Acceptance Testing shall be determined by the Steering
          Committee at the time of delivery

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          Prior to and during Acceptance Testing,  Pfizer information technology
          ("IT") staff may, upon reasonable  notice and during ordinary business
          hours, visit Neurogen to inspect the Systems and Components subject to
          Acceptance Testing. At these visits Pfizer IT staff may also test AIDD
          Units and Components;  provided,  however,  that these tests have been
          mutually  agreed.  During such process,  Neurogen staff may attend and
          provide guidance to Pfizer IT staff.

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          Within  fourteen  (14)  days  of  such  notice,   Pfizer  staff,  with
          Neurogen's  assistance will execute the Acceptance Testing protocol on
          the Pfizer AIDD Unit and notify Neurogen of such results.  If the AIDD
          Unit fails  Acceptance  Testing,

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          2.7 System Delivery, Installation, Maintenance and Repairs.

               2.7.1  Delivery.  Neurogen shall deliver or cause to be delivered

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               2.7.2  Maintenance.  For

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               after the delivery date for

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               Neurogen shall provide

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          2.8 System and  Component  Development.  During the  Contract  Period,
     Neurogen  shall  perform

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          2.9 Improvements.

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          2.10  Diligent  Efforts.  Each  party  shall use  reasonably  diligent
     efforts to achieve  the  objectives  of the  Collaboration  Program and the
     Collaboration Plan.

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3. Payments.  Pfizer shall pay Neurogen for performance of  Collaboration  Plans
and delivery of Neurogen Technology to Pfizer according to the payment schedules
set forth in this Section.

          3.1 Neurogen Technology Platform Fee. In consideration of the transfer
     to Pfizer of System and Components,

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     Pfizer shall pay

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     to Neurogen

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     twenty-seven million dollars ($ 27,000,000.00), plus

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     Such amount shall be payable according to the following schedule:

          (a)
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          (b)

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          (c)

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          (d)

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          (e)

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          (f)

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     3.2 Equipment Fees. During the Contract Period,  under the direction of the
Steering  Committee,  Pfizer  shall

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     3.3

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     3.4  Success  Payments.

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     3.5  Records.  For

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from the conclusion of each year of the Agreement,  Neurogen shall keep complete
and  accurate  records  of  its  reimbursable   expenditures   pursuant  to  the
Collaboration  Program. The records shall conform to good accounting  principles
as applied to a similar company similarly situated.  Pfizer shall have the right
at its own expense during the term of this Agreement and during the subsequent

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period  to  appoint  an  independent   certified  public  accountant  reasonably
acceptable to Neurogen to inspect said records to verify the  reimbursability of
such  expenditures.  Upon reasonable  notice by Pfizer,  Neurogen shall make its
records available for inspection by the independent  certified public accountant
during  regular  business  hours at the place or places  where such  records are
customarily  kept, to verify  accuracy  concerning the  reimbursability  of such
expenditures.  This right of inspection shall not be exercised more than once in
any calendar  year and not more than once with  respect to records  covering any
specific period of time. All information  concerning the reimbursability of such
expenditures,  and  all  information  learned  in the  course  of any  audit  or
inspection,  shall be deemed to be Neurogen Confidential Information,  except to
the extent that it is necessary for Pfizer to reveal the information in order to
enforce any rights it may have  pursuant to this  Agreement or if  disclosure is
required  by  law.  The  failure  of  Pfizer  to  request  verification  of  any
expenditures of efforts before or during the

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period  shall  be  considered  acceptance  by  Pfizer  of  the  accuracy  of the
reimbursability of such  expenditures,  and Neurogen shall have no obligation to
maintain any records pertaining to such report or statement beyond such

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period.  The  finding  of such  inspection,  if any,  shall be  binding  on both
parties.

4. Treatment of Confidential Information

     4.1 Confidentiality

          4.1.1 Pfizer and Neurogen each recognize that the other's Confidential
     Information constitutes highly valuable, confidential information.  Subject
     to the terms and conditions of this Agreement, the obligations set forth in
     Section 4.3 and the licenses  granted in Section  5.2,  Pfizer and Neurogen
     each  agree  that  during  the  term of  this  Agreement  and

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     thereafter,  it will keep  confidential,  and will cause its  Affiliates to
     keep  confidential,   all  Neurogen  Confidential   Information  or  Pfizer
     Confidential  Information,  as the case may be, that is disclosed to it, or
     to any of its  Affiliates  pursuant to this  Agreement.  Neither Pfizer nor
     Neurogen nor any of their respective Affiliates shall use such Confidential
     Information   except   as   expressly    permitted   in   this   Agreement.
     Notwithstanding  the above, if Neurogen notifies Pfizer not less than sixty
     (60) days prior to the expiration of

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     period  referred to above that certain  Neurogen  Confidential  Information
     continues  to be treated by  Neurogen  as  confidential,  Pfizer  agrees to
     extend such

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     for

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     with respect to the subject matter of this notice.

          4.1.2  Pfizer  and  Neurogen  each agree  that any  disclosure  of the
     other's Confidential  Information to any officer,  employee or agent of the
     other  party or of any of its  Affiliates  shall be made only if and to the
     extent necessary to carry out its responsibilities under this Agreement and
     shall be  limited  to the  maximum  extent  possible  consistent  with such
     responsibilities.  Pfizer  and  Neurogen  each  agree not to  disclose  the
     other's   Confidential   Information   to  any  Third   parties  under  any
     circumstance  without written  permission from the other party.  Each party
     shall take such action, and shall cause its Affiliates to take such action,
     to preserve the confidentiality of each other's Confidential Information as
     it  would  customarily  take to  preserve  the  confidentiality  of its own
     Confidential Information. Each party, upon the other's request, will return
     all the Confidential  Information  disclosed to the other party pursuant to
     this  Agreement,  including  all copies and extracts of  documents,  within
     sixty  (60) days of the  request  upon the  termination  of this  Agreement
     except for one (1) copy which may be kept for the purpose of complying with
     continuing obligations under this Agreement.

          4.1.3  Neurogen and Pfizer each  represent  that all of its employees,
     and any  subcontractors or consultants to such party,  participating in the
     Collaboration  Program  who  shall  have  access to  Pfizer  Technology  or
     Neurogen  Technology  and  Pfizer  Confidential  Information  and  Neurogen
     Confidential   Information   are  bound  by  agreement  to  maintain   such
     information in confidence.

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     4.3  Publicity.  Except as required by law,  neither party may disclose the
terms of this Agreement nor the  Collaboration  Program  described in it without
the written consent of the other party,  which consent shall not be unreasonably
withheld.

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     4.4  Disclosure of Inventions.

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     4.5 Restrictions on Transferring  Materials.  Pfizer and Neurogen recognize
that  the  chemical  protocols,  software  algorithms,  synthetic  chemical  and
biochemical   materials  which  are  part  of  Pfizer   Technology  or  Neurogen
Technology,  represent  valuable  commercial assets.  Therefore,  throughout the
Contract Period and

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thereafter,  Neurogen  and  Pfizer  agree  not to  transfer  such  materials  or
materials of the other party to any third party,  unless prior  written  consent
for any such transfer is obtained from the other party.

5. Intellectual  Property Rights.  The following  provisions relate to rights in
the intellectual  property  developed by Neurogen or Pfizer,  or both during the
course of carrying out the Collaboration Program.

     5.1 Ownership.

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     5.2 Grant of  License.  (a)  Neurogen  hereby  grants to Pfizer a

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license including the right to grant sublicenses  solely to Affiliates,  to make
and  use  Neurogen  Technology,  Neurogen  Confidential  Information,   Neurogen
Copyrights and Neurogen Patent Rights

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The license granted  hereunder is without any right to sublicense (other than to
Affiliates),  assign,  sell  or  otherwise  transfer  any  Neurogen  Technology,
Neurogen  Confidential  Information or Neurogen  Copyrights and Neurogen  Patent
Rights to any third  party.  (b) In so far as the System or Neurogen  Technology
licensed to Pfizer hereunder  included any hardware or software of a third party
such  items are listed in the  Collaboration  Plan and  Exhibit E ("Third  Party
Software"), which is attached to and made a part of this Agreement

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          5.2.1  Chemistry.   This  Agreement  confers  no  license,   right  or
     obligation  upon either  party with  respect to

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          AIDD  Software.  Pfizer  agrees  not to

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                       SECURITIES AND EXCHANGE COMMISSION].

6.  Provisions  Concerning  the Filing,  Prosecution  and  Maintenance of Patent
Rights.

     6.1 Patent  Rights  Assignments.  Each party  agrees to complete at its own
expense,  but without  further  compensation  to the other party,  any documents
necessary for either party to file patent  applications and to prosecute patents
with respect to its own Patent Rights.

     6.2 Duties.  Neurogen shall be responsible for the filing,  prosecution and
maintaining  all  Neurogen  Patent  Rights and  Copyrights  and Pfizer  shall be
responsible for filing,  prosecution and maintaining of Pfizer Patent Rights and
Copyrights.  Each  party  agrees to  cooperate  in the  preparation,  filing and
prosecution of any Patent Rights or Copyrights  arising under the  Collaboration
Plan at the other's expense. The parties neither bear nor assume any obligations
to  patent  or  copyright  any  technology   contemplated   in  this  Agreement.
Notwithstanding  anything in this Agreement to the contrary,  neither party will
file any patent application, which does not comply with such party's obligations
of confidentiality to the other party pursuant to Section 4.1.

     6.3 Further Inventions. Intellectual Property rights with respect to System
or Improvements  developed or acquired by Pfizer

                         [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION].

     7. Other Agreements.  This Agreement,  together with its Exhibits set forth
the entire agreement  between the parties with respect to the subject matter and
supersede  all other  agreements  and  understandings  between the parties  with
respect to the same.

8. Term, Termination and Disengagement.

     8.1 Term. Unless sooner terminated or extended, this Agreement shall expire

                         [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION]

 from the Effective Date.

     8.2 Events of Termination.  The following events shall constitute events of
termination ("Events of Termination"):

          (a) any  material  written  representation  or warranty by Neurogen or
     Pfizer,  or any of its  officers,  made  under or in  connection  with this
     Agreement  shall prove to have been incorrect in any material  respect when
     made.

          (b) Neurogen or Pfizer  shall fail in any material  respect to perform
     or observe any term, covenant or understanding  contained in this Agreement
     or in any of the other documents or instruments  delivered  pursuant to, or
     concurrently  with,  this  Agreement,  and any such  failure  shall  remain
     unremedied  for

                         [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION]

     after written notice to the failing party; or

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                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION]

     after written  notice,  if the failing party is working  diligently to cure
     the failure.

     8.3 Termination.

          8.3.1 Upon the occurrence of any Event of  Termination,  the party not
     responsible may, by notice to the other party, terminate this Agreement.

          8.3.2 If Pfizer  terminates this Agreement  pursuant to Section 8.3.1,
     or upon  expiration  of this  Agreement  pursuant to Section 8.1,  Pfizer's
     rights to Neurogen Technology, granted in Section 5 shall

                          [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION].

          8.3.3  Termination  of this  Agreement for any reason shall be without
     prejudice to:
          (a) the  rights  and  obligations  of the  parties  provided  in those
          Sections which by virtue of their term and condition extend beyond any
          termination of this Agreement.
          (b) Neurogen's  right to receive all payments  accrued under Section 3
          through the effective date of termination; or
          (c) any other remedies which either party may otherwise have.

9.  Representations  and  Warranties.  Neurogen and Pfizer each  represents  and
warrants as follows:
     (a) It is a corporation  duly  organized,  validly  existing and is in good
standing under the laws of Delaware,  is qualified to do business and is in good
standing as a foreign  corporation in each  jurisdiction in which the conduct of
its business of the ownership of its properties  requires such qualification and
has all requisite  power and authority,  corporate or otherwise,  to conduct its
business as now being conducted, to own, lease and operate its properties and to
execute, deliver and perform this Agreement.

     (b) The  execution,  delivery and  performance by it of this Agreement have
been duly authorized by all necessary  corporate  action and do not and will not
(i)  require  any consent or  approval  of its  stockholders,  (ii)  violate any
provision of any law, rule,  regulations,  order, writ,  judgment,  injunctions,
decree,  determination  award presently in effect having  applicability to it or
any provision of its certificate of  incorporation or by-laws or (iii) result in
a breach of or  constitute  a default  under any material  agreement,  mortgage,
lease, license,  permit or other instrument or obligation to which it is a party
or by which it or its properties may be bound or affected.

     (c)  This  Agreement  is a  legal,  valid  and  binding  obligation  of  it
enforceable by it in accordance  with its terms and  conditions,  except as such
enforceability may be limited by applicable bankruptcy,  insolvency, moratorium,
reorganization  or  similar  laws,  from  time  to  time  in  effect,  affecting
creditor's rights generally.

     (d) It is not under any obligation to any person, or entity, contractual or
otherwise,  that is conflicting or inconsistent in any respect with the terms of
this Agreement or that would impede the diligent and complete fulfillment of its
obligations. (e) It has good and marketable title to or valid leases or licenses
for, all of its properties,  rights and assets  necessary for the fulfillment of
its responsibilities under the Collaboration Program, and is subject to no claim
of any third party other than the relevant lessors or licensors.

10.  Covenants  of  Neurogen  and  Pfizer  Other  Than  Reporting  Requirements.
Throughout the Contract Period, Neurogen and Pfizer each shall:

     (a) maintain and preserve its corporate existence,  rights,  franchises and
privileges  in the  jurisdiction  of its  incorporation,  and qualify and remain
qualified as a foreign  corporation  in good  standing in each  jurisdiction  in
which such  qualification is from time to time necessary or desirable in view of
their business and operations or the ownership of their  properties.

     (b) comply in all material respects with the requirements of all applicable
laws,  rules,  regulations and orders of any government  authority to the extent
necessary to conduct the  Collaboration  Program,  except for those laws, rules,
regulations, and orders it may be contesting in good faith.

     11.  Indemnification.  Pfizer will indemnify  Neurogen and its  Affiliates,
agents and employees (the "Indemnitees") for damages, settlements,  costs, legal
fees and other expenses  incurred in connection  with a claim against any of the
Indemnitees based on

                          [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION]

provided,  however, that the foregoing shall not apply (i) if the claim is found
to be based upon the

                          [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION]

of Neurogen or (ii) if Neurogen

                         [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION].

12. Notices.  All notices shall be in writing mailed via certified mail,  return
receipt requested,  courier, or facsimile  transmission addressed as follows, or
to such other address as may be designated from time to time:

If to Pfizer:  To Pfizer at its  address as set forth at the  beginning  of this
Agreement.
Attention: President, Central Research
with copy to: Office of the General Counsel

If to Neurogen: To Neurogen at its address as set forth at the beginning of this
Agreement.
Attention: President
with copy to: General Counsel

Notices shall be deemed given as of the date received.

13.  Governing  Law.  This  Agreement  shall be  governed  by and  construed  in
accordance with the laws of the State of Delaware, USA.

14. Miscellaneous.

     14.1 Binding Effect.  This Agreement shall be binding upon and inure to the
benefit of the parties and their  respective legal  representatives,  successors
and permitted assigns.

     14.2 Headings. Paragraph headings are inserted for convenience of reference
only and do not form, a part of this Agreement.

     14.3 Counterparts.  This Agreement may be executed simultaneously in two or
more counterparts, each of which shall be deemed an original.

     14.4 Amendment, Waiver. This Agreement may be amended, modified, superseded
or canceled,  and any of the terms may be waived,  only by a written  instrument
executed  by each  party or,  in the case of  waiver,  by the  party or  parties
waiving  compliance.  The delay or  failure of any party at any time or times to
require  performance of any provisions shall in no manner affect the rights at a
later time to enforce the same.  No waiver by any party of any  condition  or of
the breach of any term  contained  in this  Agreement,  whether by  conduct,  or
otherwise,  in any one or more  instances,  shall be deemed to be, or considered
as, a further or  continuing  waiver of any such  condition  or of the breach of
such term or any other term of this Agreement.

     14.5 No third party Beneficiaries.  Except as otherwise provided in Section
11, no third party  including any employee of any party to this Agreement  shall
have or acquire any rights by reason of this  Agreement.  Nothing  contained  in
this  Agreement  shall be deemed to  constitute  the parties  partners with each
other or any third party.

     14.6  Assignment  and  Successors.  This  Agreement  may not be assigned by
either  party,  except that each party may assign this  Agreement and the rights
and interests of such party, in whole or in part, to any of its Affiliates,  any
purchaser  of  all  or  substantially  all of  its  assets  or to any  successor
corporation  resulting  from any merger or  consolidation  of such party with or
into such corporations.

     14.7 Force Majeure. Neither Pfizer nor Neurogen shall be liable for failure
of or delay in performing  obligations set forth in this Agreement,  and neither
shall be deemed in breach of its obligations, if such failure or delay is due to
natural  disasters  or any causes  reasonably  beyond  the  control of Pfizer or
Neurogen.

     14.8 Severability. If any provision of this Agreement is or becomes invalid
or is  ruled  invalid  by any  court  of  competent  jurisdiction  or is  deemed
unenforceable,  it is the  intention of the parties,  that the  remainder of the
Agreement shall not be affected.

     14.9  Y2K  Compliance.  During  the  Contract  Period  Neurogen  represents

                         [CONFIDENTIAL MATERIAL OMITTED
                          AND FILED SEPARATELY WITH THE
                       SECURITIES AND EXCHANGE COMMISSION].







IN WITNESS  WHEREOF,  the parties  have caused this  Agreement to be executed by
their duly authorized representatives.


 PFIZER INC                                  NEUROGEN CORPORATION
 By: /s/ George Milne                        By: /s/  Harry H. Penner, Jr.
 Title:  Senior Vice President               Title:   President/CEO
 Date:   June 14, 1999                       Date:    June 15, 1999










                                    EXHIBIT A (1)

                           NEUROGEN TECHNOLOGY PATENTS
                          COPYRIGHTS AND TRADE SECRETS


                                    EXHIBIT B (2)

                    AIDD DELIVERABLES AND ACCEPTANCE CRITERIA


                                    EXHIBIT C (3)

                               AIDD UNIT EQUIPMENT


                                    EXHIBIT D (4)

                               COLLABORATION PLAN


                                    EXHIBIT E (5)

                              THIRD PARTY SOFTWARE


(1)  Exhibit  A (40  pages)  omitted  pursuant  to a  request  for  confidential
     treatment and filed separately.

(2)  Exhibit  B (1  page)  omitted  pursuant  to  a  request   for  confidential
     treatment and filed separately.

(3)  Exhibit  C (20  pages)  omitted  pursuant  to a  request  for  confidential
     treatment and filed separately.

(4)  Exhibit  D (12  pages)  omitted  pursuant  to a  request  for  confidential
     treatment and filed separately.

(5)  Exhibit  E (1  page)  omitted  pursuant  to  a  request   for  confidential
     treatment and filed separately.