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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                  FORM 10-K/A4

              [ X ] ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D)
                     OF THE SECURITIES EXCHANGE ACT OF 1934
                   FOR THE FISCAL YEAR ENDED DECEMBER 31, 2001
                                       OR
             [ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                         COMMISSION FILE NUMBER 0-18311

                              NEUROGEN CORPORATION
             (Exact name of registrant as specified in its charter)

              DELAWARE                                22-2845714
  (State or other jurisdiction of                  (I.R.S. Employer
   incorporation or organization)                 Identification No.)

                          35 NORTHEAST INDUSTRIAL ROAD
                           BRANFORD, CONNECTICUT 06405
               (Address of principal executive offices) (Zip Code)

                                 (203) 488-8201
              (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, par value $.025 per share (the "Common Stock")
                                (Title of Class)

     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  period  that the
registrant  was  required  to file such  reports),  and (2) has been  subject to
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 or any amendment to this
Form 10-K. [ ]

     The  approximate  aggregate  market  value  of the  Common  Stock  held  by
non-affiliates  of the registrant was  $183,571,000  as of March 1, 2002,  based
upon the closing  price of the Common  Stock as reported on The Nasdaq  National
Market on such date.  This number is provided  only for  purposes of this report
and does not represent an admission by either the registrant or any person as to
the status of such person.

     As of March 1, 2002, the  registrant had 17,733,476  shares of Common Stock
outstanding.

                      DOCUMENTS INCORPORATED BY REFERENCE

None.

      Neurogen is filing this Form 10-K/A4 to:

(i)  include  the  certifications  required  pursuant  to  Section  906  of  the
     Sarbanes-Oxley Act of 2002 (18 U.S.C.  Section 1350) and the certifications
     required  pursuant to Rule 13a-14 or 15d-14 of the Securities  Exchange Act
     of 1934, which certifications were inadvertently omitted from the Company's
     January 9, 2002 filing on Form 10-K/A3, and

(ii) amend Part II to include the following words inadvertently deleted from the
     end of the sixth paragraph of the Liquidity and Capital  Resources  section
     of Item 7. Management's  Discussion and Analysis of Financial Condition and
     Results of Operations:

"more  expensive  than  the  previous  step,  but  actual  timing  and  cost for
completion depends on the specific progress of each product being tested."

In accordance with Rule 12b-15 of the Securities  Exchange Act of 1934, Neurogen
is also including the complete text of Item 7 and Item 14 in this Form 10-K/A.

                                     PART II

ITEM 7.   MANAGEMENT'S  DISCUSSION  AND ANALYSIS OF FINANCIAL  CONDITION AND
RESULTS OF OPERATIONS

OVERVIEW

     Since its  inception  in September  1987,  Neurogen has been engaged in the
discovery and development of drugs. The Company has not derived any revenue from
product  sales and  expects to incur  significant  losses in most years prior to
deriving  any such  product  revenues.  Revenues  to date  have  come  from five
collaborative  research  agreements,  one license  agreement and one  technology
transfer agreement.

     The  preparation  of Neurogen's  financial  statements  in conformity  with
generally accepted  accounting  principles  requires  management to make certain
estimates  and  assumptions  that  affect  the  reported  amounts  of assets and
liabilities  and disclosure of contingent  assets and liabilities at the date of
the  financial  statements  and the  reported  amounts of revenues  and expenses
during  the  reporting  period.  Management  makes  estimates  in the  areas  of
marketable  securities  and  investments,  license  and  research  arrangements,
collaboration  costs,  income  taxes,  accruals and stock  compensation.  Actual
results could differ from those estimates.

     The Company  believes the following  critical  accounting  policies  affect
management's more significant judgments and estimates used in the preparation of
Neurogen's financial statements:

Revenue Recognition

     Each of our  collaborative  research,  licensing  and  technology  transfer
agreements are significant to us. The terms of such  arrangements  may cause our
operating results to vary considerably from period to period.

     The  Company has  entered  into  collaborative  research  agreements  which
provide for the partial funding of specified  projects in exchange for the grant
of  certain  rights  related  to  potential  discoveries.  Revenue  under  these
arrangements  typically includes upfront  non-refundable  fees, ongoing payments
for  specified  levels of staffing  for  research and  milestone  payments  upon
occurrence of certain events. The upfront fees are recognized as revenue ratably
over the  period of  performance  under the  research  agreement.  The  research
funding is  recognized as revenue as the related  research  effort is performed.
Revenue  derived from the  achievement  of  milestones  is  recognized  when the
milestone event occurs.

     Neurogen has also entered into technology  transfer  agreements under which
revenue is recognized when a contractual  arrangement exists, fees are fixed and
determinable,  delivery of the  technology  has occurred and  collectibility  is
reasonably assured.  When customer  acceptance is required,  revenue is deferred
until acceptance occurs.  Where there are on-going services or obligations after
delivery,  revenue  is  recognized  over the  related  term of the  service on a
percentage of completion  basis,  unless such service is  maintenance,  which is
recognized  on a straight line basis.  For a contract  with  multiple  elements,
total contract fees are allocated to the different elements based on evidence of
fair value.

Stock-Based Compensation

     The Company  primarily grants qualified stock options for a fixed number of
shares to employees with an exercise price equal to the fair market value of the
shares at the date of grant. The Company has also issued restricted stock to key
executives which vest over specified  service periods.  The Company accounts for
grants of stock options and restricted  stock in accordance with APB Opinion No.
25, "Accounting for Stock Issued to Employees," and, accordingly,  recognizes no
compensation  expense for such  grants  when the grants  have an exercise  price
equal to the fair market value at the date of grant.

Marketable  Securities

     The Company invests in U.S.  government and corporate debt securities.  The
fair value of these securities are subject to volatility and change. The Company
considers  its  investment  portfolio  to be  available-for-sale  securities  as
defined in SFAS No. 115,  "Accounting for Certain Investments in Debt and Equity
Securities."  Marketable  securities at December 31, 2001 and 2000  consisted of
debt securities  with  maturities of three months to four years.  Securities are
available-for-sale   and  are   carried  at  fair  value  with  the   unrealized
gains/losses reported as other comprehensive  income.  Realized gains and losses
have been determined by the specific  identification  method and are included in
investment income.

RESULTS OF OPERATIONS

     Results of operations may vary from period to period  depending on numerous
factors,  including  the  timing  of  income  earned  under  existing  or future
strategic  alliances,   technology  transfer   agreements,   joint  ventures  or
financings,  if any, the progress of the Company's  research and development and
technology  transfer projects,  technological  advances and determinations as to
the commercial  potential of proposed  products.  Neurogen believes its research
and development costs may increase  significantly over the next several years as
its drug development programs progress. In addition,  general and administrative
expenses  would be expected to increase  substantially  to support any  expanded
research and development activities.

YEARS ENDED DECEMBER 31, 2001, 2000 AND 1999

     The Company's fiscal 2001 operating  revenues decreased 44 percent to $11.5
million from 2000  operating  revenues of $20.4  million,  which was an increase
from  1999  operating  revenues  of  $10.2  million.  The  decrease  in 2001 was
primarily due to a decrease in research and development  revenues resulting from
a scheduled  reduction in the Company's staffing on collaborative  programs with
Pfizer (the GABA and NPY programs  described below) and the related reduction in
discovery  research funding,  which comprised $2.9 million of operating revenues
in 2001 as compared to $8.8  million in 2000.  The  recognition  of license fees
revenue pursuant to the Pfizer Technology  Transfer Agreement  (described below)
also  decreased from $11.2 million in 2000 to $8.5 million in 2001. The increase
in 2000 operating revenues was primarily due to the recognition of $11.2 million
in license fees  revenue  under the Pfizer  Technology  Transfer  Agreement,  as
compared  to $0.5  million  under  such  agreement  in 1999,  offset by a slight
decrease in research  funding on the GABA and NPY programs  from $9.4 million in
1999 to $8.8 million in 2000.

     Research and development  expenses,  excluding  non-cash stock compensation
charges,  increased 23 percent to $34.5 million in 2001 as compared to 2000, and
also  increased  17 percent to $28.0  million in 2000 as compared  to 1999.  The
increase in 2001 was primarily due to further external development costs related
to potential drug  candidates of $5.5 million  compared to $1.4 million in 2000.
The increase in 2000, as well as the remainder of the increase in 2001,  was due
to the Company's  continued expansion of its AIDD  (TM)(Accelerated  Intelligent
Drug Discovery)  program for the discovery of new drug candidates.  Research and
development  expenses represented 84 percent, 83 percent and 85 percent of total
operating expenses (excluding non-cash stock compensation charges) for the years
ended December 31, 2001, 2000 and 1999, respectively.

     The Company expenses all research and development costs as incurred.  While
the Company maintains a system to record the level of staffing time spent on its
research  and  development  projects,  it does not  maintain a  historical  cost
accounting system with sufficient accuracy to reliably estimate its research and
development costs on a specific  project-by-project basis. Because a significant
portion of the Company's research and development  expenses,  such as laboratory
supplies, travel, information systems and services and facilities costs, benefit
multiple projects and are not individually tracked to a specific project and the
Company's  staff  timekeeping   system  does  not  account  for  differences  in
compensation  costs between lower level technicians and more senior  scientists,
the Company is unable to reliably estimate its research and development costs on
a specific project-by-project basis.

     General and administrative expenses,  excluding non-cash stock compensation
charges,  increased 15 percent to $6.6 million in 2001 from $5.7 million in 2000
and 31 percent in 2000 from $4.4 million in 1999. These increases are attributed
to additional administrative and technical services and personnel to support the
protection of Neurogen's  growing  intellectual  property  estate and to support
Neurogen's expanding research pipeline.

     Stock compensation expense, which is primarily composed of non-cash charges
to income  related  to the grant of  restricted  stock and the  modification  of
certain stock options,  was $1.5 million in 2001,  $7.1 million in 2000 and $0.1
million in 1999. In 2000 the Company recorded $6.5 million in stock compensation
expense for the vesting of restricted stock to certain employees.

     Other income,  consisting  primarily of interest  income from invested cash
and marketable  securities,  was $4.5 million in 2001,  $5.5 million in 2000 and
$3.6 million in 1999.  The  differences  in annual  income are due  primarily to
varying levels of invested funds and available interest rates.

     For the year ended  December 31, 2001,  the Company  recorded a Connecticut
income tax benefit of $1.2 million in the Statement of Operations.  This benefit
is the result of recent Connecticut legislation,  which allows certain companies
to obtain cash refunds from the State of  Connecticut at an exchange rate of 65%
of their  research  and  development  credits  in  exchange  for  foregoing  the
carryfoward of these credits into future tax years.

     The  Company  recognized  a net loss of $25.4  million  for the year  ended
December 31, 2001, $15.5 million for the year ended December 31, 2000, and $14.6
million for the year ended  December 31, 1999. The increase in the 2001 net loss
is  primarily  due to the  decrease in revenues and the increase in research and
development  and  general  and  administrative  expenses  described  above.  The
increase  in the 2000 net loss  from 1999 was due to a  non-recurring,  non-cash
$6.5 million charge  recognized in the first quarter of 2000 upon the vesting of
137,625  shares of  restricted  stock  granted to certain  employees in 1998 and
increases in research and development and general and  administrative  expenses,
as  explained  above  (net of a $0.5  million  cumulative  effect  of  change in
accounting  principle,  as  discussed  below).  These  increases in expenses are
partially offset by the recognition of $10.7 million in revenue under the Pfizer
Technology Transfer Agreement (described below).

     In December  1999,  the staff of the  Securities  and  Exchange  Commission
issued its Staff Accounting  Bulletin  ("SAB") No. 101,  Revenue  Recognition in
Financial Statements. SAB No. 101, as amended by SAB No. 101A and 101B, provides
guidance  on the  measurement  and timing of revenue  recognition  in  financial
statements of public companies.  SAB No. 101 permits application of its guidance
to be treated as a change in accounting principle in accordance with APB Opinion
No. 20,  Accounting  Changes.

     The Company  adopted the  guidance of SAB No. 101 in the fourth  quarter of
2000,  retroactive  to January 1, 2000,  and  reflected a  cumulative  effect of
change in accounting principle on prior years of $0.5 million, related to timing
of revenue  recognition on certain  non-refundable  up-front payments previously
recognized on a technology transfer agreement.

LIQUIDITY AND CAPITAL RESOURCES

     At December  31,  2001 and 2000,  cash,  cash  equivalents  and  marketable
securities were in the aggregate  $105.3 and $108.8 million,  respectively.  The
Company's  cash  and  other  short-term   investment  levels  decreased  ratably
throughout  2001 due  primarily  to the  increase  in research  and  development
expenses,  purchases  of  property,  plant and  equipment  and the  decrease  in
discovery research funding and license fees from Pfizer as described above. This
decrease was offset by $17.5 million in proceeds from a commercial term mortgage
loan  financing  completed  in  December  2001 and a $10.0  million  license fee
received under a collaboration  and license  agreement entered into with Aventis
Pharmaceuticals  Inc.  ("Aventis").  A total  amount  of  $42.4  million  of the
marketable  securities  at December  31, 2001 have  maturities  greater than one
year;  however,  the Company can and may  liquidate  such  investments  prior to
maturity to meet its strategic and/or investment objectives. The levels of cash,
cash equivalents and marketable securities have fluctuated  significantly in the
past  and  are  expected  to do so in the  future  as a  result  of the  factors
described below.

     Neurogen's  cash  requirements to date have been met by the proceeds of its
equity  financing   activities,   amounts  received  pursuant  to  collaborative
research,   licensing  or  technology   transfer   arrangements,   certain  debt
arrangements  and  interest  earned on  invested  funds.  The  Company's  equity
financing  activities  have  included  underwritten  public  offerings of common
stock,  private placement  offerings of common stock and private sales of common
stock in connection with collaborative research and licensing agreements.  Total
funding  received  from these  financing  activities  was  approximately  $146.6
million.  The Company's  expenditures  have been  primarily to fund research and
development and general and  administrative  expenses and to construct and equip
its research and development facilities.

The Company is in the early stage of product development. It has not derived any
product  revenues  from product  sales and does not expect to derive any product
revenues for at least the next several  years,  if at all. Prior to deriving any
such  product  revenues,  the Company  expects to incur  significant  losses and
negative cash flows which in the aggregate  could exceed the Company's  existing
cash  resources.  To provide cash to fund its  operations  until such time as it
achieves sustainable revenues,  the Company relies extensively on its ability to
develop  drug  discovery  programs  of  sufficient  value to either  partner the
programs  with   pharmaceutical   companies  or  raise  capital  through  equity
financings.

     To the extent  that drug  candidates  progress in the  Company's  currently
unpartnered  programs,  such as its program for the  treatment  of  inflammatory
disorders or earlier stage programs, such progress could lead to the opportunity
to  partner  on terms  which  provide  capital,  revenues  and cash flows to the
Company  or the  opportunity  to raise  capital  through  equity  offerings.  If
unpartnered  programs do not  progress  or do not  progress  on  schedule,  such
opportunities would be delayed and may not materialize at all.

     To the extent  that drug  candidates  progress in the  Company's  partnered
programs,  such as the Company's  insomnia program  partnered with Pfizer or its
depression  and anxiety  program  partnered  with Aventis,  such progress  could
result in milestone payments and additional  research and development funding to
the Company under the respective collaboration  agreements.  Such progress could
also provide the  opportunity  to raise capital  through  equity  offerings.  If
partnered  programs  do  not  progress  or do not  progress  on  schedule,  such
opportunities would be delayed and may not materialize at all.

     Lack of  progress,  scheduling  delays or failures in any of the  Company's
major programs could significantly reduce the Company's levels of revenues, cash
flows and cash  available  to fund its  business.  It could  also  significantly
increase  the  Company's  cost of capital and limit its ability to raise  equity
capital.  All of the  Company's  compounds  in  development,  whether  in  human
clinical  trials  or  not,  will  require   significant   additional   research,
development  and testing  before they can be  commercialized.  Furthermore,  the
scope, magnitude and timing of future research and development expenses, as well
as anticipated  project  completion  dates, are a series of steps,  ranging from
pre-clinical  testing to clinical studies in humans. Each step in the process is
typically  more expensive than the previous step, but actual timing and cost for
completion depends on the specific progress of each product being tested.

     While the Company cannot  accurately  predict the time required or the cost
involved in  commercializing  any one of its  candidates,  new drug  development
typically  takes many years and tens or hundreds  of  millions  of  dollars.  In
addition,  developing  new drugs is an extremely  uncertain  process  where most
candidates  fail and  uncertain  developments  such as  clinical  or  regulatory
delays,  side effects,  undesirable drug properties or ineffectiveness of a drug
candidate  would  slow or prevent  the  development  of a product.  If we or our
partners are unable to commercialize  one or more of our drug products,  we will
never  achieve  product  revenues and may  eventually  be unable to continue our
operations.  This  result  would  cause  our  shareholders  to  lose  all  or  a
substantial portion of their investment.

     The  debt  agreements  entered  into by the  Company  to date  include  the
commercial  term  mortgage  loan  financing in December  2001 with Webster Bank,
mentioned  above,  and a  construction  loan  entered  into in October 1999 with
Connecticut  Innovations Inc. Total proceeds  received under these agreements as
of December  31, 2001,  are $22.5  million.  Of these  amounts  received,  as of
December 31, 2001, $22.4 million remained outstanding.  An approximate aggregate
amount  of $1.4  million  is due and  payable  in each of the next  five  years.
Thereafter, approximately $15.4 million is payable in regular installments until
the scheduled  maturity dates. As of December 31, 2001,  Neurogen is not engaged
in any significant lease or capital expenditure commitments.

     The  Company  plans  to use  its  cash,  cash  equivalents  and  marketable
securities  for its research and  development  activities,  working  capital and
general corporate purposes.  Neurogen anticipates that its current cash balance,
as  supplemented by research  funding  pursuant to its  collaborative  research,
licensing and  technology  transfer  agreements,  will be sufficient to fund its
current  and  planned  operations  through at least  2004.  However,  Neurogen's
funding requirements may change and will depend upon numerous factors, including
but not  limited to, the  progress of the  Company's  research  and  development
programs,  the timing and results of preclinical  testing and clinical  studies,
the timing of regulatory approvals, technological advances, determinations as to
the  commercial  potential of its proposed  products,  the status of competitive
products and the ability of the Company to establish and maintain  collaborative
arrangements  with  others  for the  purpose  of funding  certain  research  and
development   programs,   conducting  clinical  studies,   obtaining  regulatory
approvals  and, if such  approvals  are  obtained,  manufacturing  and marketing
products.  Many of these  factors  could  significantly  increase the  Company's
expenses and use of cash. The Company  anticipates  that it may augment its cash
balance through financing transactions, including the issuance of debt or equity
securities  and further  corporate  alliances.  No assurances  can be given that
adequate levels of additional  funding can be obtained on favorable terms, if at
all.

     As of December 31, 2001,  the Company had  approximately  $83.6 million and
$6.1  million  of  net  operating  loss  and  research  and  development  credit
carryforwards,  respectively,  available for federal income tax purposes,  which
expire in the years 2004 through 2021. The Company also had approximately  $73.3
million  and $3.5  million  of  Connecticut  state  tax net  operating  loss and
research and development credit carryforwards, respectively, which expire in the
years  2002  through  2021.  The  Company  has  applied  to  exchange  year 2000
Connecticut  research  and  development  credits  for cash  proceeds  under  new
Connecticut  tax law  provisions  (as  mentioned  above).  Because of "change in
ownership"  provisions of the Tax Reform Act of 1986, the Company's  utilization
of its net operating loss and research and development credit  carryforwards may
be subject to an annual limitation in future periods.

COLLABORATIVE RESEARCH AGREEMENTS

     In  December  2001,  Neurogen  entered  into a  collaboration  and  license
agreement with Aventis (the "Aventis  Agreement") pursuant to which Aventis made
an initial  payment of $10  million and agreed,  among other  things,  to fund a
specified level of resources for at least three years for Neurogen's program for
the  discovery  and research of CRF1  receptor-based  drugs for a broad range of
applications,  including the  therapeutic  treatment of  depression  and anxiety
disorders.  Aventis has the option to extend the discovery  and research  effort
for an  additional  two years.  Neurogen is also  eligible to receive  milestone
payments  if certain  compound  discovery,  product  development  or  regulatory
objectives  are  achieved  subject  to the  collaboration.  In  return,  Aventis
received  the  exclusive  worldwide  rights to develop,  manufacture  and market
collaboration  drugs that act through the CRF1 receptor,  with no limitations as
to the therapeutic indications for which the drugs may be used. Aventis will pay
Neurogen  royalties  based  upon net sales  levels,  if any,  for  collaboration
products. Also under the agreement,  Aventis is responsible for funding the cost
of  development,  including  clinical  trials,  manufacturing  and  marketing of
collaboration products, if any.

     In June  1999,  Neurogen  and Pfizer  entered  into a  technology  transfer
agreement (the "Pfizer Technology Transfer Agreement").  Under the terms of this
agreement, Pfizer has agreed to pay Neurogen a total of up to $27.0 million over
a three  year  period for the  licensing  and  transfer  to Pfizer of certain of
Neurogen's  AIDD  technologies  for the  discovery of new drugs,  along with the
installation  of an AIDD  system.  Additional  payments are also  possible  upon
Pfizer's  successful  utilization  of this  technology.  Pfizer  has  received a
non-exclusive  license for certain AIDD  intellectual  property and the right to
employ this technology in its own drug development  programs. As of December 31,
2001,  Pfizer had provided  $23.5 million in license fees pursuant to the Pfizer
Technology  Transfer  Agreement.

     In 1992,  Neurogen  entered into a  collaborative  research  agreement with
Pfizer  (the "1992  Pfizer  Agreement")  pursuant  to which  Pfizer made a $13.8
million equity investment in the Company and agreed, among other things, to fund
a specified level of resources for up to five years (later extended as described
below) for Neurogen's  research  programs for the discovery of GABA-based  drugs
for the  treatment of anxiety and  cognitive  disorders.  In 1994,  Neurogen and
Pfizer entered into a second collaborative  research agreement (the "1994 Pfizer
Agreement")  pursuant to which Pfizer made a $9.9 million  equity  investment in
the Company  and  agreed,  among  other  things,  to fund a  specified  level of
resources  for  up to  four  years  (later  extended  as  described  below)  for
Neurogen's  research  program for the  development  of GABA-based  drugs for the
treatment of sleep disorders. As of December 31, 2001, Pfizer had provided $43.2
million and $14.1  million of research  funding to the Company and $0.5  million
and $0.3  million  for the  achievement  of  certain  clinical  development  and
regulatory  milestones  pursuant to the 1992 and 1994 Pfizer  Agreements and the
extensions  of such  agreements,  respectively.  Neurogen is eligible to receive
additional  milestone payments of up to $12.0 million and $3.0 million under the
1992 and 1994  Pfizer  Agreements,  respectively,  if  certain  development  and
regulatory  objectives  are  achieved  regarding  its  products  subject  to the
collaboration.  In  return,  under  the  two  agreements,  Pfizer  received  the
exclusive rights to manufacture and market  collaboration drugs that act through
the GABA system for the treatment of anxiety, cognition enhancement,  depression
or insomnia.  Pfizer will pay Neurogen royalties based upon net sales levels, if
any, for such products. Under the agreements,  Pfizer is responsible for funding
the cost of all clinical  development and the  manufacturing  and marketing,  if
any, of drugs developed from the collaborations.

     On three  occasions,  Neurogen  and  Pfizer  extended  Neurogen's  research
efforts  under the 1992 and 1994 Pfizer  Agreements.  Pursuant to the  extension
agreements, which terminated in December 2001, Neurogen received $2.9 million in
2001 (which amount is included in the above-described cumulative totals received
for the 1992 and 1994 Pfizer Agreements) for research and development funding of
the Company's  GABA-based  anxiolytic,  cognitive  enhancer and sleep  disorders
projects.  With the  scheduled  conclusions  of the research  funding  under the
Pfizer  Agreements  mentioned  above,  employee  resources  have been shifted to
ongoing projects which are currently unpartnered and for which Neurogen owns all
commercial rights.

Recently Issued Accounting Pronouncements

     In  August 2001,  the  Financial  Accounting  Standards  Board  issued SFAS
No. 144,  "Accounting for the Impairment or Disposal of Long-Lived Assets." SFAS
No. 144  supercedes  SFAS No. 121,  "Accounting for the Impairment of Long-Lived
Assets  and for  Long-Lived  Assets  to be  Disposed  Of,"  in that it  excludes
goodwill from its impairment  scope and allows for different  approaches in cash
flow  estimation.  However,  SFAS No. 144 retains the fundamental  provisions of
SFAS No. 121 for recognition and measurement of the impairment of (a) long-lived
assets to be held and used and  (b) long-lived  assets to be  disposed  of other
than by sale.  Neurogen  has not adopted the  provisions  of SFAS  No. 144 as of
December 31, 2001. However, the Company believes that the implementation of this
standard  will not have a  material  effect on its  results  of  operations  and
financial  position,  since the  impairment  assessment  under  SFAS  No. 144 is
largely unchanged from SFAS No. 121 and management is not currently aware of any
significant long-lived assets impaired or planned for disposal.

                                     PART IV

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

(a)

     (1)  Financial Statements

          Reference is made to the Index to Financial Statements under Item 8 in
          Part II of Form 10-K/A3 filed January 9, 2003,  where these  documents
          are listed.

     (2)  Financial Statement Schedule

          Note:  Schedules  are omitted as not  applicable or not required or on
          the basis that the information is included in the financial statements
          or notes thereto.

     (3)  Exhibits

          See Exhibit Index.

(b)  Reports on Form 8-K

     The Company  filed two current  reports on Form 8-K on December 21, 2001 to
     submit for filing  News  Releases of the Company  dated  December  20, 2001
     announcing an exclusive worldwide  collaboration agreement between Neurogen
     and  Aventis  Pharma to  develop  new drugs for the  treatment  of  several
     disorders based on specified Company compounds, and the preliminary results
     from a Phase IIA clinical  study of the Company's  lead drug  candidate for
     the  treatment of anxiety  disorders,  where the subjects  tested  showed a
     trend toward efficacy that did not achieve statistical significance.

                                   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.

                                                   NEUROGEN CORPORATION

                                                   /S/ STEPHEN R. DAVIS
                                               By:______________________________
                                                  Stephen R. Davis
                                                  Executive Vice President and
                                                  Chief Business Officer

Date: January 21, 2003

                                 CERTIFICATIONS

I, William H. Koster, certify that:

1.   I have reviewed  this annual  report on Form  10-K/A3,  as modified by Form
     10-K/A4, of Neurogen Corporation;

2.   Based on my  knowledge,  this  annual  report  does not  contain any untrue
     statement of a material fact or omit to state a material fact  necessary to
     make the statements  made, in light of the  circumstances  under which such
     statements  were made, not misleading with respect to the period covered by
     this annual report; and

3.   Based on my  knowledge,  the  financial  statements,  and  other  financial
     information included in this annual report,  fairly present in all material
     respects the financial  condition,  results of operations and cash flows of
     the registrant as of, and for, the periods presented in this annual report.

                                               By:  /s/ William H. Koster
                                                    ____________________________

                                                    William H. Koster
                                                    President and
                                                    Chief Executive Officer
                                                    Date:  January 20, 2003

I, Stephen R. Davis, certify that:

1.   I have reviewed  this annual  report on Form  10-K/A3,  as modified by Form
     10-K/A4, of Neurogen Corporation;

2.   Based on my  knowledge,  this  annual  report  does not  contain any untrue
     statement of a material fact or omit to state a material fact  necessary to
     make the statements  made, in light of the  circumstances  under which such
     statements  were made, not misleading with respect to the period covered by
     this annual report; and

3.   Based on my  knowledge,  the  financial  statements,  and  other  financial
     information included in this annual report,  fairly present in all material
     respects the financial  condition,  results of operations and cash flows of
     the registrant as of, and for, the periods presented in this annual report.

                                               By:  /s/ Stephen R. Davis
                                                    ____________________________

                                                    Stephen R. Davis
                                                    Executive Vice President
                                                    and Chief Business Officer
                                                    Date:  January 20, 2003

EXHIBIT INDEX

EXHIBIT
NUMBER                               DESCRIPTION
-------   ----------------------------------------------------------------------
3.1    -  Restated   Certificate  of   Incorporation,  filed   June   17,   1994
          (incorporated by reference to Exhibit 4.1  to  Registration  Statement
          No. 33-81268 on form S-8).

3.2    -  By-Laws, as  amended  (incorporated by reference to Exhibit 3.6 to the
          Company's Form 10-K for the fiscal year ended December 31, 1993).

10.1   -  Neurogen  Corporation  Stock  Option Plan, as amended (incorporated by
          reference to Exhibit  10.1 to  the  Company's Form 10-K for the fiscal
          year ended December 31, 1991).

10.2    - Form of Stock Option  Agreement  currently used in connection with the
          grant  of  options  under  Neurogen   Corporation  Stock  Option  Plan
          (incorporated by reference to Exhibit 10.2 to the Company's Form 10-K
          for the fiscal year ended December 31, 1992).

10.3    - Neurogen   Corporation   1993  Omnibus   Incentive  Plan,  as  amended
          (incorporated by reference to  Exhibit 10.3 to the Company's Form 10-K
          for the fiscal year ended December 31, 1993).

10.4    - Form of Stock Option  Agreement  currently used in connection with the
          grant of options under  Neurogen  Corporation  1993 Omnibus  Incentive
          Plan (incorporated by reference to Exhibit 10.4 to the Company's Form
          10-K for the fiscal year ended December 31, 1993).

10.5    - Neurogen Corporation 1993 Non-Employee  Directors Stock Option Program
          (incorporated  by reference to Exhibit 10.5 to the Company's Form 10-K
          for the fiscal year ended December 31, 1993).

10.6    - Form of Stock Option  Agreement  currently used in connection with the
          grant  of  options  under  Neurogen   Corporation  1993   Non-Employee
          Directors Stock Option Program  (incorporated  by reference to Exhibit
          10.6 to the Company's Form 10-K for the fiscal year ended December 31,
          1993).

10.7    - Employment  Contract  between the Company  and Harry H.  Penner,  Jr.,
          dated as of October 12, 1993  (incorporated  by  reference  to Exhibit
          10.7 to the Company's Form 10-K for the fiscal year ended December 31,
          1993).

10.8    - Employment Contract between the Company and John F. Tallman,  dated as
          of December 1, 1993 (incorporated by reference to Exhibit 10.25 to the
          Company's Form 10-Q for  the  quarterly  period  ended  September  30,
          1994).

10.9    - Form of Proprietary Information and Inventions  Agreement(incorporated
          by reference to Exhibit  10.31 to  Registration Statement No. 33-29709
          on Form S-1).

10.10   - Collaborative  Research  Agreement  and License and Royalty  Agreement
          between  the  Company  and  Pfizer  Inc,  dated as of  January 1, 1992
          (CONFIDENTIAL  TREATMENT  REQUESTED)  (incorporated  by  reference  to
          Exhibit  10.35 to the  Company's  Form 10-K for the fiscal  year ended
          December 31, 1991).

10.11   - Letter Agreement between the Company and Barry M. Bloom, dated January
          12, 1994  (incorporated by reference to Exhibit 10.25 to the Company's
          Form 10-K for the fiscal year ended December 31, 1993).

10.12   - Letter  Agreement  between the Company and Robert H. Roth, dated April
          14, 1994  (incorporated by reference to Exhibit 10.26 to the Company's
          Form 10-K for the fiscal year ended December 31, 1994).

10.13   - Collaborative  Research  Agreement  and License and Royalty  Agreement
          between  the  Company  and  Pfizer  Inc,  dated  as of  July  1,  1994
          (CONFIDENTIAL  TREATMENT  REQUESTED)  (incorporated  by  reference  of
          Exhibit 10.1 to the Company's Form 10-Q for the quarterly period ended
          June 30, 1994).

10.14   - Stock  Purchase  Agreement  between the Company and Pfizer dated as of
          July  1,  1994  (incorporated  by  reference  to  Exhibit  10.2 to the
          Company's Form 10-Q for the quarterly period ended June 30, 1994).

10.15   - Collaboration  and License  Agreement and Screening  Agreement between
          the Company and Schering-Plough  Corporation  (CONFIDENTIAL  TREATMENT
          REQUESTED) (incorporated by reference to Exhibit 10.1 to the Company's
          Form 8-K dated July 28, 1995).

10.16   - Lease Agreement between the Company and Commercial Building Associates
          dated as of August 30,  1995  (incorporated  by  reference  to Exhibit
          10.27 to the Company's Form 10-Q for the quarterly period ended
          September 30, 1995).

10.17   - Collaborative  Research Agreement between the Company and Pfizer dated
          as  of   November   1,   1995   (CONFIDENTIAL   TREATMENT   REQUESTED)
          (incorporated by reference to Exhibit 10.1 of the Company's Form 8-K
          dated November 1, 1995).

10.18   - Development and  Commercialization  Agreement  between the Company and
          Pfizer dated as of November 1, 1995 (CONFIDENTIAL TREATMENT REQUESTED)
          (incorporated  by  reference to Exhibit 10.2 of the Company's Form 8-K
          dated November 1, 1995).

10.19   - Stock  Purchase  Agreement  between the Company and Pfizer dated as of
          November  1, 1995   (incorporated   by  reference  to Exhibit  10.3 of
          the Company's Form 8-K dated November 1, 1995).

10.20   - Stock  Purchase  Agreement  dated  as of  November  25,  1996  between
          American Home Products  Corporation,  acting through its  Wyeth-Ayerst
          Laboratories   Division,   and  Neurogen   Corporation   (CONFIDENTIAL
          TREATMENT  REQUESTED) (incorporated  by  reference  to Exhibit 10.1 of
          the Company's Form 8-K dated March 31, 1997).

10.21   - Technology  agreement  between the Company and Pfizer Inc, dated as of
          June  15,  1999  (CONFIDENTIAL  TREATMENT  REQUEST)  (Incorporated  by
          reference  to  Exhibit  10.27  to  the  Company's  Form  10-Q  for the
          quarterly  period ended June 30, 1999).

10.22   - Employment  Contract  between the Company and Alan J. Hutchison, dated
          as of December 1, 1997  (incorporated  by  reference  to Exhibit 10.28
          to the  Company's Form 10-K  for the  fiscal year  ended  December 31,
          1999).

10.23   - Employment  Contract  between the Company  and Stephen R. Davis, dated
          as of December 1, 1997 (incorporated  by  reference  to Exhibit  10.29
          to the Company's Form  10-K for the  fiscal  year  ended  December 31,
          1999).

10.24   - Employment  Contract  between  the Company  and Kenneth R. Shaw, dated
          as of December 1, 1999  (incorporated  by  reference  to Exhibit 10.30
          to the  Company's Form  10-K for the  fiscal  year ended  December 31,
          1999).

10.25   - Neurogen Corporation 2000 Non-Employee  Directors Stock Option Program
          (incorporated  by  reference to Exhibit 10.31  to  the Company's  Form
          10-Q for the quarterly period ended June 30, 2000).

10.26   - Form  of the Non-Qualified Stock  Option  Agreement  currently used in
          connection  with  the  grant of options under the Neurogen Corporation
          2000  Non-Employee  Directors  Stock  Option  Program (incorporated by
          reference  to  Exhibit  10.32  to  the  Company's  Form 10-Q  for  the
          quarterly period ended June 30,2000).

10.27   - Registration Rights  Agreement  dated  as of June 26, 2000 between the
          Company and the Purchasers listed on Exhibit  A thereto  (incorporated
          by  reference  to  Exhibit  10.33 to  the Company's  Form 10-Q for the
          quarterly  period ended June 30, 2000).

10.28   - Severance Agreement between the Company and John F. Tallman,  dated as
          of January 15, 2001 (incorporated by reference to Exhibit 10.28 to the
          Company's Form 10-Q for the quarterly period ended March 31, 2001).

10.29   - Amended and Restated Neurogen Corporation  2001 Stock  Option Plan, as
          amended  and  restated  effective  September  4, 2001 (incorporated by
          reference to  Exhibit  10.29  to  the  Company's  Form  10-Q  for  the
          quarterly period ended September 30, 2001).

10.30   - Form of Incentive Stock Option Agreement  currently used in connection
          with the grant of options  under the  Amended  and  Restated  Neurogen
          Corporation 2001 Stoc k Option  Plan  (incorporated  by  reference  to
          Exhibit  10.30  to  the  Company's  Form 10-Q for the quarterly period
          ended September 30, 2001).

10.31   - Form of the  Non-Qualified  Stock Option  Agreement  currently used in
          connection  with the grant of options  under the Amended and  Restated
          Neurogen Corporation 2001 Stock Option Plan (incorporated by reference
          to Exhibit 10.31 to the Company's Form 10-Q for the  quarterly  period
          ended September 30, 2001).

10.32   - Form of Neurogen Special Committee Stock Option Plan (incorporated  by
          reference to  Exhibit  10.32  to  the  Company's  Form  10-Q  for  the
          quarterly period ended September 30, 2001).

10.33   - Employment  Agreement between the Company and William H. Koster, dated
          as of September 4, 2001 (incorporated by reference to Exhibit 10.33 to
          the Company's Form 10-Q for the quarterly period ended  September  30,
          2001).

10.34   - Severance  Agreement  between the Company  and Harry H.  Penner,  Jr.,
          dated as of  September 7,  2001  (incorporated by reference to Exhibit
          10.34 to the Company's  Form  10-Q  for  the  quarterly  period  ended
          September 30, 2001).

10.35   - Collaboration and License Agreement dated  as  of  December  11,  2001
          between the Company  and  Aventis  Pharmaceuticals  Inc. (CONFIDENTIAL
          TREATMENT REQUESTED)  (incorporated by  reference to Form 10-K/A2  for
          the period ended December 31, 2001).

10.36   - Modification  Agreement dated as of December 1, 2000 between  Neurogen
          Properties LLC and Connecticut Innovations, Incorporated (incorporated
          by reference to Form 10-K/A3 for the period ended December 31, 2001).

10.37   - Construction Loan Agreement  dated as  of  October  22,  1999  between
          Neurogen  Properties  LLC  and  Connecticut Innovations,  Incorporated
          (incorporated  by  reference  to  Form  10-K/A3  for  the period ended
          December 31, 2001).

10.38   - Commercial Term Note  dated as  of  December  21,  2001  held  by  the
          Company and payable to Webster Bank (incorporated by reference to Form
          10-K/A3 for the period ended December 31, 2001).

10.39   - Commercial Loan  Agreement  dated as  of  December  21,  2001  between
          Webster Bank  and  the Company  (incorporated  by  reference  to  Form
          10-K/A3 for the period ended  December 31, 2001).

21.1    - Subsidiary of the registrant(incorporated by reference to Exhibit 21.1
          to the Company's Form 10-K  for  the  fiscal  year  ended December 31,
          1999).

23.1    - Consent   of  PricewaterhouseCoopers   LLP,  Independent   Accountants
          (incorporated by reference  to  Form  10-K/A3  for  the  period  ended
          December 31, 2001).

24.1    - Powers of Attorney of Frank C. Carlucci,  Robert H. Roth,  John Simon,
          John  F. Tallman,  Robert  N. Butler,  Jeffrey  J. Collinson , Suzanne
          H. Woolsey, Mark Novitch, Barry M. Bloom,  Julian  C.  Baker, Felix J.
          Baker and Craig Saxton (incorporated  by reference to Form 10-K/A3 for
          the period ended December 31, 2001).

99.1    - Certification Pursuant to 18 U.S.C. Section 1350, as adopted  pursuant
          to Section 906 of the  Sarbanes-Oxley  Act of 2002.

99.2    - Certification Pursuant to 18 U.S.C. Section 1350, as adopted  pursuant
          to Section 906 of the  Sarbanes-Oxley  Act of 2002.

                                                                    EXHIBIT 99.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Neurogen  Corporation (the "Company") on
Form  10-K/A3,  as modified by Form 10-K/A4,  for the period ended  December 31,
2001, as filed with the  Securities  and Exchange  Commission on the date hereof
(the "Report"),  I, William H. Koster,  President and Chief Executive Officer of
the Company,  certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that to my knowledge:

(1)  The Report fully complies with the  requirements  of section 13(a) or 15(d)
     of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

(2)  The information  contained in the Report fairly  presents,  in all material
     respects, the financial condition and results of operations of the Company.

                                               By:  /s/ William H. Koster
                                                    ----------------------------
                                                    William H. Koster
                                                    President and
                                                    Chief Executive Officer
                                                    Date:  January 20, 2003

                                                                    EXHIBIT 99.2

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Neurogen  Corporation (the "Company") on
Form  10-K/A3,  as modified by Form 10-K/A4,  for the period ended  December 31,
2001, as filed with the  Securities  and Exchange  Commission on the date hereof
(the "Report"), I, Stephen R. Davis, Executive Vice President and Chief Business
Officer of the Company,  certify pursuant to 18 U.S.C.  Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to my knowledge:

(1)  The Report fully complies with the  requirements  of section 13(a) or 15(d)
     of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

(2)  The information  contained in the Report fairly  presents,  in all material
     respects, the financial condition and results of operations of the Company.

                                               By:  /s/ Stephen R. Davis
                                                    ----------------------------
                                                    Stephen R. Davis
                                                    Executive Vice President and
                                                    Chief Business Officer
                                                    Date:  January 20, 2003
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