AMERICAN BIOGENETIC SCIENCES, INC.
                                      * * *
                                    BY - LAWS
                                      * * *
                         AS AMENDED AS OF JUNE 10, 1996


                                    ARTICLE I

                                     OFFICES

           Section 1. The registered offices shall be in the City of Wilmington,
County of New Castle, State of Delaware.

           Section 2. The corporation may also have offices at such other places
both within and without the State of Delaware as the board of directors may from
time to time determine or the business of the corporation may require.


                                   ARTICLE II
                            MEETINGS OF STOCKHOLDERS

           Section 1. All  meetings  of the  stockholders  for the  election  of
directors  shall be held at such  place as may be fixed from time to time by the
board of directors, or at such other place either within or without the State of
Delaware as shall be designated  from time to time by the board of directors and
stated in the notice of the  meeting.  Meetings  of  stockholders  for any other
purpose  may be held at such  time and  place,  within or  without  the State of
Delaware,  as shall be stated in the notice of the meeting or in a duly executed
waiver of notice thereof.

           Section 2.  Annual  meetings  of  stockholders,  shall be held on the
first Tuesday of June if not a legal holiday,  and if a legal  holiday,  then on
the next secular day following, at 10:00 A.M.,








or at such other date and time as shall be  designated by the board of directors
and  stated  in the  notice  of the  meeting,  at which  they  shall  elect by a
plurality  vote a board of directors,  and transact  such other  business as may
properly be brought before the meeting.

           Section 3. Written  notice of the annual  meeting  stating the place,
date and hour of the meeting shall be given to each stockholder entitled to vote
at such  meeting  not less than ten nor more than sixty days  before the date of
the meeting.

           Section  4. The  officer  who has  charge of the stock  ledger of the
corporation  shall  prepare and make,  at least ten days before every meeting of
stockholders,  a  complete  list  of the  stockholders  entitled  to vote at the
meeting,  arranged  in  alphabetical  order,  and  showing  the  address of each
stockholder and the number of shares registered in the name of each stockholder.
Such list shall be open to the examination of any  stockholder,  for any purpose
germane to the meeting, during ordinary business hours, for a period of at least
ten days  prior to the  meeting,  either at a place  within  the city  where the
meeting  is to be held,  which  place  shall be  specified  in the notice of the
meeting, or, if not so specified,  at the place where the meeting is to be held.
The list shall also be  produced  and kept at the time and place of the  meeting
during the whole time thereof,  and may be inspected by any  stockholder  who is
present.

           Section 5. Special meetings of the  stockholders,  for any purpose or
purposes,  unless  otherwise  prescribed  by  statute or by the  certificate  of
incorporation,  may be  called  by the  president  and  shall be  called  by the
president  or  secretary at the request in writing of a majority of the board of
directors,  or at the  request in writing of  stockholders  owning a majority in
amount of the entire


                                       -2-




capital stock of the  corporation  issued and  outstanding and entitled to vote.
Such request shall state the purpose or purposes of the proposed meeting.

           Section 6.  Written  notice of a special  meeting  stating the place,
date and hour of the meeting  and the purpose or purposes  for which the meeting
is called,  shall be given not less than ten nor more than sixty days before the
date of the meeting, to each stockholder entitled to vote at such meeting.

           Section 7. Business transacted at any special meeting of stockholders
shall be limited to the purposes stated in the notice.

           Section  8.  The  holders  of a  majority  of the  stock  issued  and
outstanding  and entitled to vote thereat,  present in person or  represented by
proxy,  shall  constitute a quorum at all meetings of the  stockholders  for the
transaction  of  business  except as  otherwise  provided  by  statute or by the
certificate of incorporation.  If, however,  such quorum shall not be present or
represented at any meeting of the  stockholders,  the  stockholders  entitled to
vote thereat,  present in person or  represented  by proxy,  shall have power to
adjourn the meeting from time to time, without notice other than announcement at
the meeting,  until a quorum shall be present or represented.  At such adjourned
meeting at which a quorum  shall be present or  represented  any business may be
transacted  which  might  have been  transacted  at the  meeting  as  originally
notified.  If the  adjournment  is for more than  thirty  days,  or if after the
adjournment  a new record date is fixed for the adjourned  meeting,  a notice of
the adjourned  meeting shall be given to each  stockholder of record entitled to
vote at the meeting.


                                       -3-




           Section 9. When a quorum is present at any  meeting,  the vote of the
holders of a majority  of the stock  having  voting  power  present in person or
represented  by proxy shall decide any  question  brought  before such  meeting,
unless the question is one upon which by express provision of the statutes or of
the  certificate  of  incorporation,  a different vote is required in which case
such express provision shall govern and control the decision of such question.

           Section  10.  Unless   otherwise   provided  in  the  certificate  of
incorporation  each  stockholder  shall at every meeting of the  stockholders be
entitled to one vote in person or by proxy for each share of the  capital  stock
having  voting  power held by such  stockholder,  but no proxy shall be voted on
after three years from its date, unless the proxy provides for a longer period.

           Section  11.  Unless   otherwise   provided  in  the  certificate  of
incorporation,  any action required to be taken at any annual or special meeting
of  stockholders  of the  corporation,  or any action  which may be taken at any
annual or special meeting of such stockholders,  may be taken without a meeting,
without prior notice and without a vote, if a consent in writing,  setting forth
the action so taken,  shall be signed by the holders of outstanding stock having
not less than the minimum  number of votes that would be  necessary to authorize
or take such action at a meeting at which all shares  entitled  to vote  thereon
were  present and voted.  Prompt  notice of the taking of the  corporate  action
without a meeting by less than unanimous written consent shall be given to those
stockholders who have not consented in writing.


                                       -4-




                                   ARTICLE III

                                    DIRECTORS
 
           Section 1. The number of directors  which shall  constitute the whole
board shall be not less than three (3) nor more than nine (9).  The exact number
of directors within the maximum and minimum limitation specified herein shall be
fixed from time to time by resolution  of the board of directors.  The directors
shall be elected as provided  in Section 2 of this  Article,  and each  director
elected  shall  hold  office  until his  successor  is  elected  and  qualified.
Directors need not be stockholders.

           Section 2. The directors shall have the power,  from time to time, to
increase  or  decrease  their  own  number,   within  the  maximum  and  minimum
limitations  specified  therein,  by  resolution  of  the  board  of  directors.
Vacancies and newly  created  directorships  resulting  from any increase in the
authorized number of directors may be filled by a majority of the directors then
in office,  though less than a quorum, or by a sole remaining director,  and the
directors so chosen  shall hold office until the next annual  election and until
their successors are duly elected and shall qualify, unless sooner displaced. If
there are no directors in office,  then an election of directors  may be held in
the manner  provided by  statute.  If, at the time of filling any vacancy or any
newly created di rectorship,  the directors then in office shall constitute less
than a majority of the whole  board (as con  stituted  immediately  prior to any
such increase),  the Court of Chancery may, upon  application of any stockholder
or  stockholders  holding at least ten percent of the total number of the shares
at the time outstanding  having the right to vote for such directors,  summarily
order an election to be held to fill


                                       -5-




any such vacancies or newly created  directorships,  or to replace the directors
chosen by the directors then in office.

           Section 3. The  business  of the  corporation  shall be managed by or
under the direction of its board of directors which may exercise all such powers
of the  corporation and do all such lawful acts and things as are not by statute
or by the certificate of  incorporation or by these by-laws directed or required
to be exercised or done by the stockholders.

                       MEETINGS OF THE BOARD OF DIRECTORS

           Section  4.  The  board  of  directors  of the  corporation  may hold
meetings,  both  regular  and  special,  either  within or without  the State of
Delaware.

           Section 5. The first meeting of each newly elected board of directors
shall  be held at such  time  and  place  as  shall  be fixed by the vote of the
stockholders  at the  annual  meeting  and no  notice of such  meeting  shall be
necessary to the newly  elected  directors in order  legally to  constitute  the
meeting,  provided a quorum shall be present. In the event of the failure of the
stockholders to fix the time or place of such first meeting of the newly elected
board of  directors,  or in the event  such  meeting is not held at the time and
place so fixed by the  stockholders,  the  meeting  may be held at such time and
place as shall  be  specified  in a notice  given as  hereinafter  provided  for
special  meetings  of the  board of  directors,  or as shall be  specified  in a
written waiver signed by all of the directors.

           Section 6.  Regular  meetings of the board of  directors  may be held
without  notice  at such  time and at such  place as shall  from time to time be
determined by the board.


                                       -6-




           Section  7.  Special  meetings  of the  board  may be  called  by the
president on ten days' notice to each director,  either personally or by mail or
by telegram;  special  meetings shall be called by the president or secretary in
like manner and on like notice on the written  request of two  directors  unless
the board consists of only one director; in which case special meetings shall be
called by the  president  or  secretary in like manner and on like notice on the
written request of the sole director.

           Section 8. At all  meetings of the board a majority of the  directors
shall  constitute  a quorum for the  transaction  of  business  and the act of a
majority  of the  directors  present at any  meeting at which  there is a quorum
shall  be  the  act  of the  board  of  directors,  except  as may be  otherwise
specifically  provided by statute or by the certificate of  incorporation.  If a
quorum  shall  not be  present  at any  meeting  of the board of  directors  the
directors  present  thereat may adjourn the meeting  from time to time,  without
notice other than announcement at the meeting, until a quorum shall be present.

           Section  9.  Unless  otherwise   restricted  by  the  certificate  of
incorporation or these by- laws, any action required or permitted to be taken at
any meeting of the board of directors or of any  committee  thereof may be taken
without a meeting, if all members of the board or committee, as the case may be,
consent  thereto in  writing,  and the  writing or  writings  are filed with the
minutes of proceedings of the board or committee.

           Section  10.  Unless  otherwise  restricted  by  the  certificate  of
incorporation  or these by- laws,  members  of the  board of  directors,  or any
committee designated by the board of directors,  may participate in a meeting of
the board of directors,  or any committee,  by means of conference  telephone or
similar communications  equipment by means of which all persons participating in
the


                                       -7-




meeting  can  hear  each  other,  and  such  participation  in a  meeting  shall
constitute presence in person at the meeting.

                             COMMITTEES OF DIRECTORS

           Section 11. The board of  directors  may, by  resolution  passed by a
majority of the whole board, designate one or more committees, each committee to
consist  of one or more of the  directors  of the  corporation.  The  board  may
designate one or more directors as alternate  members of any committee,  who may
replace any absent or disqualified member at any meeting of the committee.

           Any such  committee,  to the extent provided in the resolution of the
board of directors,  shall have and may exercise all the powers and authority of
the board of  directors  in the  management  of the  business and affairs of the
corporation,  and may authorize the seal of the corporation to be affixed to all
papers  which may  require  it;  but no such  committee  shall have the power or
authority in reference to amending the certificate of incorporation, adopting an
agreement of merger or consolidation, recommending to the stockholders the sale,
lease or exchange of all or substantially all of the corporation's  property and
assets,  recommending to the  stockholders a dissolution of the corporation or a
revocation of a dissolution,  or amending the by-laws of the  corporation;  and,
unless the resolution or the certificate of incorporation  expressly so provide,
no such committee  shall have the power or authority to declare a dividend or to
authorize the issuance of stock.  Such  committee or committees  shall have such
name or names as may be determined  from time to time by  resolution  adopted by
the board of directors.


                                       -8-




           Section 12. Each committee shall keep regular minutes of its meetings
and report the same to the board of directors when required.

                            COMPENSATION OF DIRECTORS

           Section  13.  Unless  otherwise  restricted  by  the  certificate  of
incorporation or these by- laws, the board of directors shall have the authority
to fix the compensation of directors.  The directors may be paid their expenses,
if any, of  attendance at each meeting of the board of directors and may be paid
a fixed sum for attendance at each meeting of the board of directors or a stated
salary as director. No such payment shall preclude any director from serving the
corporation in any other capacity and receiving compensation  therefor.  Members
of special or standing committees may be allowed like compensation for attending
committee meetings.

                              REMOVAL OF DIRECTORS

           Section  14.  Unless  otherwise  restricted  by  the  certificate  of
incorporation  or by law, any  director or the entire board of directors  may be
removed,  with or without cause, by the holders of a majority of shares entitled
to vote at an election of directors.

                                   ARTICLE IV
                                     NOTICES

           Section 1.  Whenever,  under the provisions of the statutes or of the
certificate of incorporation or of these by-laws, notice is required to be given
to any director or stockholder, it shall


                                       -9-




not be  construed  to mean  personal  notice,  but such  notice  may be given in
writing, by mail,  addressed to such director or stockholder,  at his address as
it appears on the records of the corporation,  with postage thereon prepaid, and
such  notice  shall be  deemed  to be given at the time  when the same  shall be
deposited in the United  States mail.  Notice to directors  may also be given by
telegram.

           Section 2.  Whenever  any notice is  required  to be given  under the
provisions of the statutes or of the  certificate of  incorporation  or of these
by-laws,  a waiver thereof in writing,  signed by the person or persons entitled
to said notice, whether before or after the time stated therein, shall be deemed
equivalent thereto.

                                    ARTICLE V
                                    OFFICERS

           Section 1. The  officers  of the  corporation  shall be chosen by the
board of  directors  and  shall be a  chairman  of the  board,  a  president,  a
vice-president,  a secretary  and a treasurer.  The board of directors  may also
choose  additional  vice-presidents,  and one or more assistant  secretaries and
assistant  treasurers.  Any  number of offices  may be held by the same  person,
unless the certificate of incorporation or these by-laws otherwise provide.

           Section 2. The board of  directors  at its first  meeting  after each
annual  meeting  of  stockholders   shall  choose  a  president,   one  or  more
vice-presidents, a secretary and a treasurer.

           Section 3. The board of directors may appoint such other officers and
agents as it shall deem  necessary  who shall hold their  offices for such terms
and shall  exercise  such powers and perform such duties as shall be  determined
from time to time by the board.


                                      -10-




           Section 4. The salaries of all officers and agents of the corporation
shall be fixed by the board of directors.

           Section 5. The  officers of the  corporation  shall hold office until
their successors are chosen and qualify. Any officer elected or appointed by the
board of  directors  may be  removed  at any time by the  affirmative  vote of a
majority of the board of directors.  Any vacancy  occurring in any office of the
corporation shall be filled by the board of directors.

                            THE CHAIRMAN OF THE BOARD

           Section 6. The  chairman  of the board  shall be the chief  executive
officer of the  corporation,  shall preside at all meetings of the  shareholders
and the board of  directors  shall have  general  and active  management  in the
business of the corporation and shall see that all orders and resolutions of the
board of directors are carried into effect.  He shall, to the same extent as the
president,  have  authority to execute  bonds,  mortgages  and other  contracts,
except  where  required by law to be  otherwise  signed and  executed and except
where the signing and  execution  thereof  shall be  expressly  delegated by the
board of directors to some other officer or agent of the corporation.

                                  THE PRESIDENT

           Section  7.  The  president  shall,  unless  another  officer  of the
corporation  is  designated  as such,  be the  chief  operating  officer  of the
corporation;  in the absence of the chairman of the board,  shall preside at all
meetings of the  stockholders  and the board of directors and shall perform such
other  duties  and have such  other  powers as the  board of  directors  and the
chairman of the board may


                                      -11-




from time to time  prescribe.  He may, to the same extent as the chairman of the
board,  execute bonds,  mortgages and other contracts,  except where required by
law to be  otherwise  signed and  executed  and  except  where the  signing  and
execution thereof shall be expressly delegated by the board of directors to some
other officer or agent of the corporation.

                               THE VICE-PRESIDENTS

           Section  8. In the  absence of the  president  or in the event of his
inability or refusal to act, the  vice-president  (or in the event there be more
than one  vice-president,  the  vice-presidents  in the order  designated by the
directors,  or in the  absence  of any  designation,  then in the order of their
election) shall perform the duties of the president,  and when so acting,  shall
have  all  the  powers  of and be  subject  to all  the  restrictions  upon  the
president.  The  vice-presidents  shall  perform such other duties and have such
other powers as the board of directors may from time to time prescribe.

                      THE SECRETARY AND ASSISTANT SECRETARY

           Section 9. The  secretary  shall  attend all meetings of the board of
directors and all meetings of the stockholders and record all the proceedings of
the  meetings of the  corporation  and of the board of directors in a book to be
kept for that purpose and shall perform like duties for the standing  committees
when  required.  He shall give, or cause to be given,  notice of all meetings of
the  stockholders  and  special  meetings of the board of  directors,  and shall
perform  such other  duties as may be  prescribed  by the board of  directors or
president,  under whose  supervision  he shall be. He shall have  custody of the
corporate seal of the corporation and he, or an assistant secretary, shall have


                                      -12-




authority to affix the same to any instrument  requiring it and when so affixed,
it may be  attested  by his  signature  or by the  signature  of such  assistant
secretary.  The  board of  directors  may give  general  authority  to any other
officer to affix the seal of the  corporation  and to attest the affixing by his
signature.

           Section 10. The  assistant  secretary,  or if there be more than one,
the assistant  secretaries in the order determined by the board of directors (or
if there be no such  determination,  then in the order of their election) shall,
in the absence of the  secretary or in the event of his  inability or refusal to
act,  perform  the duties and  exercise  the powers of the  secretary  and shall
perform  such other  duties and have such other powers as the board of directors
may from time to time prescribe.


                     THE TREASURER AND ASSISTANT TREASURERS

           Section 11. The  treasurer  shall have the  custody of the  corporate
funds and securities  and shall keep full and accurate  accounts of receipts and
disbursements in books belonging to the corporation and shall deposit all moneys
and other valuable  effects in the name and to the credit of the  corporation in
such depositories as may be designated by the board of directors.

           Section 12. He shall disburse the funds of the  corporation as may be
ordered  by  the  board  of   directors,   taking   proper   vouchers  for  such
disbursements,  and shall render to the president and the board of directors, at
its regular meetings,  or when the board of directors so requires, an account of
all  his  transactions  as  treasurer  and of  the  financial  condition  of the
corporation.

           Section 13. If required by the board of directors,  he shall give the
corporation a bond (which shall be renewed every six years) in such sum and with
such surety or sureties as shall be


                                      -13-




satisfactory  to the board of  directors  for the  faithful  performance  of the
duties of his office and for the restoration to the corporation,  in case of his
death,  resignation,  retirement or removal from office,  of all books,  papers,
vouchers,  money and other  property of whatever kind in his possession or under
his control belonging to the corporation.

           Section 14. The assistant  treasurer,  or if there shall be more than
one, the assistant  treasurers in the order determined by the board of directors
(or if  there be no such  determination,  then in the  order of their  election)
shall,  in the  absence of the  treasurer  or in the event of his  inability  or
refusal to act,  perform the duties and exercise the powers of the treasurer and
shall  perform  such other  duties  and have such  other  powers as the board of
directors may from time to time prescribe.


                                   ARTICLE VI
                              CERTIFICATE OF STOCK

           Section 1. Every holder of stock in the corporation shall be entitled
to have a  certificate,  signed  by, or in the name of the  corporation  by, the
chairman or  vice-chairman  of the board of  directors,  or the  president  or a
vice-president and the treasurer or an assistant treasurer,  or the secretary or
an assistant secretary of the corporation, certifying the number of shares owned
by him in the corporation.

           Section  2.  Any of or all the  signatures  on a  certificate  may be
facsimile.  In case any officer,  transfer  agent or registrar who has signed or
whose facsimile  signature has been placed upon a certificate  shall have ceased
to be such officer, transfer agent or registrar before such certificate is


                                      -14-




issued,  it may be issued by the corporation  with the same effect as if he were
such officer, transfer agent or registrar at the date of issue.

                                LOST CERTIFICATES

           Section 3. The board of  directors  may direct a new  certificate  or
certificates   to  be  issued  in  place  of  any  certificate  or  certificates
theretofore  issued by the  corporation  alleged  to have been  lost,  stolen or
destroyed,  upon the making of an affidavit of that fact by the person  claiming
the certificate of stock to be lost, stolen or destroyed.  When authorizing such
issue of a new  certificate or  certificates  the board of directors may, in its
discretion  and as a condition  precedent to the issuance  thereof,  require the
owner of such lost,  stolen or destroyed  certificate  or  certificates,  or his
legal  representative,  to advertise the same in such manner as it shall require
and/or to give the  corporation a bond in such sum as it may direct as indemnity
against any claim that may be made against the  corporation  with respect to the
certificate alleged to have been lost, stolen or destroyed.

                                TRANSFER OF STOCK

           Section 4. Upon surrender to the corporation or the transfer agent of
the  corporation  of a certificate  for shares duly endorsed or  accompanied  by
proper evidence of succession, assignation or authority to transfer, it shall be
the duty of the  corporation to issue a new  certificate to the person  entitled
thereto, cancel the old certificate and record the transaction upon its books.



                                      -15-




                               FIXING RECORD DATE

           Section  5.  In  order  that  the   corporation   may  determine  the
stockholders  entitled to notice of or to vote at any meeting of stockholders or
any adjournment  thereof,  or to express consent to corporate  action in writing
without a meeting,  or  entitled  to receive  payment of any  dividend  or other
distribution  or allotment of any rights,  or entitled to exercise any rights in
respect of any change, conversion or exchange of stock or for the purpose of any
other lawful action,  the board of directors may fix, in advance, a record date,
which  shall not be more than  sixty nor less than ten days  before  the date of
such  meeting,   nor  more  than  sixty  days  prior  to  any  other  action.  A
determination  of  stockholders  of record entitled to notice of or to vote at a
meeting of stockholders shall apply to any adjournment of the meeting; provided,
however, that the board of directors may fix a new record date for the adjourned
meeting.

                             REGISTERED STOCKHOLDERS

           Section  6.  The  corporation  shall be  entitled  to  recognize  the
exclusive  right of a person  registered  on its books as the owner of shares to
receive  dividends,  and to vote as such owner, and to hold liable for calls and
assessments a person  registered on its books as the owner of shares,  and shall
not be bound to  recognize  any  equitable or other claim to or interest in such
share or shares on the part of any other  person,  whether  or not it shall have
express or other notice  thereof,  except as  otherwise  provided by the laws of
Delaware.



                                      -16-




                                   ARTICLE VII
                               GENERAL PROVISIONS
                                    DIVIDENDS

           Section  1.  Dividends  upon the  capital  stock of the  corporation,
subject to the provisions of the  certificate of  incorporation,  if any, may be
declared by the board of directors at any regular or special  meeting,  pursuant
to law. Dividends may be paid in cash, in property,  or in shares of the capital
stock, subject to the provisions of the certificate of incorporation.

           Section 2. Before payment of any dividend, there may be set aside out
of any funds of the corporation  available for dividends such sum or sums as the
directors  from time to time, in their  absolute  discretion,  think proper as a
reserve or reserves to meet contingencies,  or for equalizing dividends,  or for
repairing  or  maintaining  any property of the  corporation,  or for such other
purpose  as  the  directors  shall  think  conducive  to  the  interest  of  the
corporation,  and the  directors  may modify or abolish any such  reserve in the
manner in which it was created.

                                ANNUAL STATEMENT

           Section  3. The  board of  directors  shall  present  at each  annual
meeting,  and at any special meeting of the stockholders when called for by vote
of the stockholders, a full and clear statement of the business and condition of
the corporation.



                                      -17-




                                     CHECKS

           Section  4.  All  checks  or  demands  for  money  and  notes  of the
corporation  shall be signed by such officer or officers or such other person or
persons as the board of directors may from time to time designate.

                                   FISCAL YEAR

           Section  5.  The  fiscal  year of the  corporation  shall be fixed by
resolution of the board of directors.

                                      SEAL

           Section 6. The corporate seal shall have  inscribed  thereon the name
of the corporation,  the year of its organization and the words "Corporate Seal,
Delaware".  The seal may be used by  causing  it or a  facsimile  thereof  to be
impressed or affixed or reproduced or otherwise.

                                 INDEMNIFICATION

           Section 7. The corporation  shall indemnify its officers,  directors,
employees and agents to the extent  permitted by the General  Corporation Law of
Delaware.

                                  ARTICLE VIII
                                   AMENDMENTS

           Section 1. These  by-laws may be altered,  amended or repealed or new
by-laws may be adopted by the  stockholders  or by the board of directors,  when
such power is conferred upon the


                                      -18-




board of directors by the certificate of incorporation at any regular meeting of
the  stockholders  or of the board of directors or at any special meeting of the
stockholders  or of the  board  of  directors  if  notice  of  such  alteration,
amendment,  repeal or adoption of new by-laws be contained in the notice of such
special  meeting.  If the power to adopt,  amend or repeal  by-laws is conferred
upon the board of directors by the  certificate  of  incorporation  it shall not
divest or limit the power of the stockholders to adopt, amend or repeal by-laws.



                                      -19-