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                                                                     EXHIBIT 3.3


                             AMENDMENT OF BYLAWS OF
                       LIGAND PHARMACEUTICALS INCORPORATED
                               December 11, 1997


          Article III, Section 7 of the Bylaws of the Corporation is amended in
its entirety to provide as follows:


                   "Section 7. Notice of Special Meetings. Special meetings of
          the Board may be called by the Chief Executive Officer or President on
          no less than twenty-four (24) hours notice to each Director either
          personally, or by telephone, mail, telegram or facsimile; special
          meetings shall be called by the Chief Executive Officer, 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 Chief Executive Officer,
          President or Secretary in like manner and on like notice on the
          written request of the sole Director. A written waiver of notice,
          signed by the person entitled thereto, whether before or after the
          time of the meeting stated therein, shall be deemed equivalent to
          notice."


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                       CERTIFICATE OF AMENDMENT OF BYLAWS
                                       OF
                       LIGAND PHARMACEUTICALS INCORPORATED


          I, William L. Respess, hereby certify:

          1. That I am the duly elected and acting Secretary of Ligand
Pharmaceuticals Incorporated, a Delaware corporation (the "Corporation"); and

          2. That the attached amendment to Article III, Section 7 of the Bylaws
is a true and correct copy of the amendment to the Bylaws of the Corporation
duly adopted by the Board of Directors of the Corporation at a meeting on
December 11,1997.

          IN WITNESS WHEREOF, I have executed this Certificate on December 11,
1997.


                                                   /s/ WILLIAM L. RESPESS
                                                   -----------------------------
                                                   William L. Respess, Secretary
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                           AMENDED AND RESTATED BYLAWS
                                       OF
                       LIGAND PHARMACEUTICALS INCORPORATED

                                    ARTICLE I

                                     OFFICES

        Section 1. Registered Office. The registered office shall be in the City
of Dover, County of Kent, State of Delaware.

        Section 2. Other Offices. 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. Place of Meetings. All meetings of the stockholders for the
election of Directors shall be held in the City of San Diego, State of
California, 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.


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        Section 2. Annual Meeting.

                   (a) The annual meeting of the stockholders of the
corporation, for the purpose of election of Directors and for such other
business as may lawfully come before it, shall be held on such date and at such
time as may be designated from time to time by the Board of Directors.

                   (b) At an annual meeting of the stockholders, only such
business shall be conducted as shall have been properly brought before the
meeting. To be properly brought before an annual meeting, business must be: (A)
specified in the notice of meeting (or any supplement thereto) given by or at
the direction of the Board of Directors, (B) otherwise properly brought before
the meeting by or at the direction of the Board of Directors, or (C) otherwise
properly brought before the meeting by a stockholder. For business to be
properly brought before an annual meeting by a stockholder, the stockholder must
have given timely notice thereof in writing to the Secretary of the corporation.
To be timely, a stockholder's notice must be delivered to or mailed and received
at the principal executive offices of the corporation not less than one hundred
twenty (120) calendar days in advance of the date specified in the corporation's
proxy statement released to stockholders in connection with the previous year's
annual meeting of stockholders; provided, however, that in the event that no
annual meeting was held in the previous year or the date of the annual
meeting has been changed by more than thirty (30) days from the date
contemplated at the time of the previous year's proxy 

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statement, notice by the stockholder to be timely must be so received a
reasonable time before the solicitation is made. A stockholder's notice to the
Secretary shall set forth as to each matter the stockholder proposes to bring
before the annual meeting: (i) a brief description of the business desired to be
brought before the annual meeting and the reasons for conducting such business
at the annual meeting, (ii) the name and address, as they appear on the
corporation's books, of the stockholder proposing such business, (iii) the class
and number of shares of the corporation which are beneficially owned by the
stockholder, (iv) any material interest of the stockholder in such business and
(v) any other information that is required to be provided by the stockholder
pursuant to Regulation 14A under the Securities Exchange Act of 1934, as amended
(the "1934 Act"), in his capacity as a proponent to a stockholder proposal.
Notwithstanding the foregoing, in order to include information with respect to a
stockholder proposal in the proxy statement and form of proxy for a
stockholder's meeting, stockholders must provide notice as required by the
regulations promulgated under the 1934 Act. Notwithstanding anything in these
Bylaws to the contrary, no business shall be conducted at any annual meeting
except in accordance with the procedures set forth in this paragraph (b). The
chairman of the annual meeting shall, if the facts warrant, determine and
declare at the meeting that business was not properly brought before the meeting
and in accordance with the provisions of this paragraph (b), and, if he should
so determine, he shall so declare at the meeting that any such


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business not properly brought before the meeting shall not be transacted.

                   (c) Only persons who are nominated in accordance with the
procedures set forth in this paragraph (c) shall be eligible for election as
Directors. Nominations of persons for election to the Board of Directors of the
corporation may be made at a meeting of stockholders by or at the direction of
the Board of Directors or by any stockholder of the corporation entitled to vote
in the election of Directors at the meeting who complies with the notice
procedures set forth in this paragraph (c). Such nominations, other than those
made by or at the direction of the Board of Directors, shall be made pursuant to
timely notice in writing to the Secretary of the corporation in accordance with
the provisions of paragraph (b) of this Section 2. Timely notice shall also be
given of any stockholder's intention to cumulate votes in the election of
Directors at a meeting if cumulative voting is available. Such stockholder's
notice shall set forth (i) as to each person, if any, whom the stockholder
proposes to nominate for election or re-election as a Director: (A) the name,
age, business address and residence address of such person, (B) the principal,
occupation or employment of such person, (C) the class and number of shares of
the corporation which are beneficially owned by such person, (D) a description
of all arrangements or understandings between the stockholder and each
nominee and any other person or persons (naming such person or persons) pursuant
to which the nominations are to be made by the stockholder, and (E) any other
information relating to such 


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person that is required to be disclosed in solicitations of proxies for election
of Directors, or is otherwise required, in each case pursuant to Regulation 14A
under the 1934 Act (including without limitation such person's written consent
to being named in the proxy statement, if any, as a nominee and to serving as a
Director if elected); and (ii) as to such stockholder giving notice, the
information required to be provided pursuant to paragraph (b) of this Section 2
and, if cumulative voting is available to such stockholder, whether such
stockholder intends to request cumulative voting in the election of Directors at
the meeting. At the request of the Board of Directors, any person nominated by a
stockholder for election as a Director shall furnish to the Secretary of the
corporation that information required to be set forth in the stockholder's
notice of nomination which pertains to the nominee. No person shall be eligible
for election as a Director of the corporation unless nominated in accordance
with the procedures set forth in this paragraph (c). The chairman of the meeting
shall, if the facts warrant, determine and declare at the meeting that a
nomination was not made in accordance with the procedures prescribed by these
Bylaws, and if he should so determine, he shall so declare at the meeting, and
the defective nomination shall be disregarded.

        Section 3. Notice of Annual Meeting. 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


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meeting not less than ten (10) nor more than sixty (60) days before the date of
the meeting.

        Section 4. Voting List. 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. 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 at least
ten percent (10%) of the entire capital stock of the corporation issued and
outstanding and entitled to vote. Such request shall state the purpose or
purposes of the proposed

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meeting. The place, date and time of any special meeting shall be determined by
the Board of Directors. Such determination shall include the record date for
determining the stockholders having the right of and to vote at such meeting.

        Section 6. Notice of Special Meeting. 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 (10)
nor more than sixty (60) days before the date of the meeting, to each
stockholder entitled to vote at such meeting.

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

        Section 8. Quorum and Adjournments.

                   (a) 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 

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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.

                   (b) 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 9. Voting Rights.

                   (a) 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.

                   (b) At all elections of Directors of the corporation each
stockholder having voting power shall be entitled to exercise the right of
cumulative voting as provided in the Certificate of Incorporation.

                   (c) On and after the date upon which this corporation is no
longer subject to Section 2115 of the 

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California Corporations Code (the "Record Date"), cumulative voting shall no
longer be available to the stockholders and Section 9(b) shall no longer be
applicable.

        Section 10. Action Without Meeting. No action shall be taken by the
stockholders of the corporation except at an annual or special meeting of
stockholders called in accordance with these Bylaws, and no action shall be
taken by the stockholders by written consent.

                                   ARTICLE III

                                    DIRECTORS

        Section 1. Number, Term of Office and Qualification. The number of
Directors which shall constitute the whole Board shall not be less than seven
nor more than eleven. Within the limits above specified, the number of Directors
shall be determined by resolution of the Board of Directors or by the
stockholders at the annual meeting of the stockholders, except 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. Vacancies. 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 

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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
Directorship, the Directors then in office shall constitute less than a majority
of the whole Board (as constituted 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 any such vacancies or newly created Directorships,
or to replace the Directors chosen by the Directors then in office.

        Section 3. Powers. 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 Bylaws directed or
required to be exercised or done by the stockholders.

        Section 4. Regular and Special Meetings. The Board of Directors of the
corporation may hold meetings, both regular and special, either within or
without the State of Delaware.

        Section 5. Annual Meeting. 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 

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first meeting of the newly elected Board of Directors, or in the event such
meeting nominee and any other person or persons (naming such person or persons)
pursuant to which the nominations are to be made by the stockholder, and (E) any
other information relating to such 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. Notice of Regular Meetings. 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.

        Section 7. Notice of Special Meetings. Special meetings of the Board may
be called by the president on four (4) days' notice to each Director by mail or
48 hours' notice to each Director either personally 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. Quorum. 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


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from time to time, without notice other than announcement at the meeting, until
a quorum shall be present.

        Section 9. Action Without Meeting. Unless otherwise restricted by the
Certificate of Incorporation or these Bylaws, 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. Meetings by Telephone Conference Calls. Unless otherwise
restricted by the Certificate of Incorporation or these Bylaws, 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 meeting can hear each other, and such
participation in a meeting shall constitute presence in person at the meeting.

        Section 11. Committees. 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.


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        In the absence of disqualification of a member of a committee, the
member or members thereof present at any meeting and not disqualified from
voting, whether or not he or they constitute a quorum, may unanimously appoint
another member of the Board of Directors to act at the meeting in the place of
any such absent or disqualified member.

        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 Bylaws 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.


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        Each committee shall keep regular minutes of its meetings and report the
same to the Board of Directors when required.

        Section 12. Fees and Compensation. Unless otherwise restricted by the
Certificate of Incorporation or these Bylaws, 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.

        Section 13. Removal. Subject to any limitations imposed by law or the
Certificate of Incorporation, the Board of Directors, or any individual
Director, may be removed from office at any time, with or without cause, by the
affirmative vote of the holders of at least a majority of shares entitled to
vote at an election of Directors.


                                   ARTICLE IV

                                     NOTICES

        Section 1. Notice. Whenever, under the provisions of the statutes or of
the Certificate of Incorporation or of these Bylaws, notice is required to be
given to any Director or stockholder, it shall not be construed to mean personal
notice,


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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. Waiver of Notice. Whenever any notice is required to be given
under the provisions of the statutes or of the Certificate of Incorporation or
of these Bylaws, 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. Enumeration. The officers of the corporation shall be chosen
by the Board of Directors and shall be a president and a secretary. The Board of
Directors may elect from among its members a Chairman of the Board and a Vice
Chairman of the Board. The Board of Directors may also choose a treasurer and/or
one or more vice presidents, assistant secretaries and assistant treasurers. Any
number of offices may be held by the same person, unless the Certificate of
Incorporation or these Bylaws otherwise provide.

        The salaries of all officers and agents of the corporation shall be
fixed by the Board of Directors.

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        Section 2. Election or Appointment. The Board of Directors at its first
meeting after each annual meeting of stockholders shall choose a president and a
secretary and may choose a vice president and a treasurer.

                   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.

        Section 3. Tenure, Removal and Vacancies. The officers of the
corporation shall hold office until their successors are chosen and qualified.
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.

        Section 4. Chairman of the Board. The Chairman of the Board, if any,
shall preside at all meetings of the Board of Directors and of the stockholders
at which he shall be present. He shall have and may exercise such powers as are,
from time to time, assigned to him by the Board and as may be provided by law.

        Section 5. Vice Chairman of the Board. In the absence of the Chairman of
the Board, the Vice Chairman of the Board, if any, shall preside at all meetings
of the Board of Directors and of the stockholders at which he shall be present.
He shall have and may exercise such powers as are, from time to time, assigned
to him by the Board and as may be provided by law.

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        Section 6. President. The president shall be the chief executive officer
of the corporation; and in the absence of the Chairman and Vice Chairman of the
Board he shall preside at all meetings of the stockholders and the Board of
Directors; he shall have general and active management of the business of the
corporation and shall see that all orders and resolutions of the Board of
Directors are carried into effect.

        He shall execute bonds, mortgages and other contracts requiring a seal,
under the seal of the corporation, except where required or permitted 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.

        Section 7. Vice President. In the absence of the president or in the
event of his inability or refusal to act, the vice president, if any, (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.

        Section 8. Secretary. 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


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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
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 9. Assistant Secretary. 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.

        Section 10. Treasurer. 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


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corporation in such depositories as may be designated by the Board of
Directors.

        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.

        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 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 11. Assistant Treasurer. 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.

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                                   ARTICLE VI

                              CERTIFICATE OF STOCK

        Section 1. Certificates of Stock. 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.

        Certificates may be issued for partly paid shares and in such case upon
the face or back of the certificates issued to represent any such partly paid
shares, the total amount of the consideration to be paid therefor, and the
amount paid thereon shall be specified.

        If the corporation shall be authorized to issue more than one class of
stock or more than one series of any class, the powers, designations,
preferences and relative, participating, optional or other special rights of
each class of stock or series thereof and the qualification, limitations or
restrictions of such preferences and/or rights shall be set forth in full or
summarized on the face or back of the certificate which the corporation shall
issue to represent such class or series of stock, provided that, except as
otherwise provided in section 202 of the General Corporation Law of Delaware, in
lieu of the foregoing requirements, there may be set forth on the face or back
of the certificate which the corporation shall issue to represent such class or
series of stock, a statement that the 


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corporation will furnish without charge to each stockholder who so requests the
powers, designations, preferences and relative, participating, optional or other
special rights of each class of stock or series thereof and the qualifications,
limitations or restrictions of such preferences and/or rights.

        Section 2. Execution of Certificates. Any of or all the signatures on
the 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 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.

        Section 3. Lost Certificates. 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 


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against the corporation with respect to the certificate alleged to have been
lost, stolen or destroyed.

        Section 4. Transfer of Stock. 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.

        Section 5. Fixing Record Date. In order that the corporation may
determine the stockholders entitled to notice of or to vote at any meeting of
stockholder or any adjournment thereof, 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 (60) nor less than
ten (10) days before the date of such meeting, nor more than sixty (60) 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.

        Section 6. Registered Stockholders. 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


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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.


                                   ARTICLE VII

                                 INDEMNIFICATION

        Section 1. Indemnification of Directors and Executive Officers. The
corporation shall indemnify its Directors and executive officers to the fullest
extent not prohibited by the Delaware General Corporation Law; provided,
however, that the corporation may limit the extent of such indemnification by
individual contracts with its Directors and executive officers; and, provided,
further, that the corporation shall not be required to indemnify any Director or
executive officer in connection with any proceeding or part thereof) initiated
by such person or any proceeding by such person against the corporation or its
Directors, officers, employees or other agents unless (i) such indemnification
is expressly required to be made by law, (ii) the proceeding was authorized by
the Board of Directors of the corporation, (iii) such indemnification is
provided by the corporation, in its sole discretion, pursuant to the powers
vested in the corporation under the Delaware General Corporation Law.

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   26
          Section 2. Indemnification of Other Officers, Employees and Other
Agents. The corporation shall have power to indemnify its other officers,
employees and other agents as set forth in the Delaware General Corporation Law.

        Section 3. Good Faith.

                   (a) For purposes of any determination under this Bylaw, a
Director or executive officer shall be deemed to have acted in good faith and in
a manner he reasonably believed to be in or not opposed to the best interests of
the corporation, and, with respect to any criminal action or proceeding, to have
had no reasonable cause to believe that his conduct was unlawful, if his action
is based on information, opinions, reports and statements, including financial
statements and other financial data, in each case prepared or presented by:

                            (1) one or more officers or employees of the
                   corporation whom the Director or executive officer believed
                   to be reliable and competent in the matters presented,

                            (2) counsel, independent accountants or other
                   persons as to matters which the Director or executive officer
                   believed to be within such person's professional competence;
                   and

                            (3) with respect to a Director, a committee of the
                   Board upon which such Director does not serve, as to matters
                   within such Committee's designated authority, which 


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                   committee the Director believes to merit confidence; so long 
                   as, in each case, the Director or executive officer acts
                   without knowledge that would cause such reliance to be
                   unwarranted.

                   (b) The termination of any proceeding by judgment, order,
settlement, conviction or upon a plea of nolo contendere or its equivalent shall
not, of itself, create a presumption that the person did not act in good faith
and in a manner which he reasonably believed to be in or not opposed to the best
interests of the corporation, and, with respect to any criminal proceeding, that
he had reasonable cause to believe that his consent was unlawful.

                   (c) The provisions of this Section 3 shall not be deemed to
be exclusive or to limit in any way the circumstances in which a person may be
deemed to have met the applicable standard of conduct set forth by the Delaware
General Corporation Law.

        Section 4. Expenses. The corporation shall advance, prior to the final
disposition of any proceeding, promptly following request therefor, all expenses
incurred by any Director or executive officer in connection with such proceeding
upon receipt of an undertaking by or on behalf of such person to repay said
amounts if it should be determined ultimately that such person is not entitled
to be indemnified under this Bylaw or otherwise.

        Notwithstanding the foregoing, unless otherwise determined pursuant to
Section 4 of this Bylaw, no advance shall 


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be made by the corporation if a determination is reasonably and promptly made
(i) by the Board of Directors by a majority vote of a quorum consisting of
Directors who were not parties to the proceeding, or (ii) if such quorum is not
obtainable, or, even if obtainable, a quorum of disinterested Directors so
directs, by independent legal counsel in a written opinion, that the facts known
to the decision-making party at the time such determination is made demonstrate
clearly and convincingly that such person acted in bad faith or in a manner that
such person did not believe to be in or not opposed to the best interests of the
corporation.

        Section 5. Enforcement. Without the necessity of entering into an
express contract, all rights to indemnification and advances to Directors and
executive officers under this Bylaw shall be deemed to be contractual rights and
be effective to the same extent and as if provided for in a contract between the
corporation and the Director or executive officer. Any right to indemnification
or advances granted by this Bylaw to a Director or executive officer shall be
enforceable by or on behalf of the person holding such right in any court of
competent jurisdiction if (i) the claim for indemnification or advances is
denied, in whole or in part, or (ii) no disposition of such claim is made within
ninety (90) days of request therefor. The claimant in such enforcement action,
if successful in whole or in part, shall be entitled to be paid also the expense
of prosecuting his claim. The corporation shall be entitled to raise as a
defense to any such action that the claimant has not met the standards of


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   29
conduct that make it permissible under the Delaware General Corporation Law for
the corporation to indemnify the claimant for the amount claimed. Neither the
failure of the corporation (including its Board of Directors, independent legal
counsel or its stockholders) to have made a determination prior to the
commencement of such action that indemnification of the claimant is proper in
the circumstances because he has met the applicable standard of conduct set
forth in the Delaware General Corporation Law, nor an actual determination by
the corporation (including its Board of Directors, independent legal counsel or
its stockholders) that the claimant has not met such applicable standard of
conduct, shall be a defense to the action or create a presumption that claimant
has not met the applicable standard of conduct.

        Section 6. Non-Exclusivity of Rights. The rights conferred on any person
by this Bylaw shall not be exclusive of any other right which such person may
have or hereafter acquire under any statute, provision of the Certificate of
Incorporation, Bylaws, agreement, vote of stockholders or disinterested
Directors or otherwise, both as to action in his official capacity and as to
action in another capacity while holding office. The corporation is specifically
authorized to enter into individual contracts with any or all of its Directors,
officers, employees or agents respecting indemnification and advances, to the
fullest extent not prohibited by the Delaware General Corporation Law.

        Section 7. Survival of Rights. The rights conferred on any person by
this Bylaw shall continue as to a person who has ceased 


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   30
to be a Director, officer, employee or other agent and shall inure to the
benefit of the heirs, executors and administrators of such a person.

        Section 8. Insurance. To the fullest extent permitted by the Delaware
General Corporation Law, the corporation, upon approval by the Board of
Directors, may purchase insurance on behalf of any person required or permitted
to be indemnified pursuant to this Bylaw.

        Section 9. Amendments. Any repeal or modification of this Bylaw shall
only be prospective and shall not affect the rights under this Bylaw in effect
at the time of the alleged occurrence of any action or omission to act that is
the cause of any proceeding against any agent of the corporation.

        Section 10. Saving Clause. If this Bylaw or any portion hereof shall be
invalidated on any ground by any court of competent jurisdiction, then the
corporation shall nevertheless indemnify each Director and executive officer to
the full extent not prohibited by any applicable portion of this Bylaw that
shall not have been invalidated, or by any other applicable law.

        Section 11. Certain Definitions. For the purposes of this Bylaw, the
following definitions shall apply:

                   (a) The term "proceeding" shall be broadly construed and
shall include, without limitation, the investigation, preparation, prosecution,
defense, settlement, arbitration and appeal of, and the giving of the testimony
in, any threatened, pending or completed action, suit or proceeding, whether
civil, criminal, administrative or investigative.

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   31
                   (b) The term "expenses" shall be broadly construed and shall
include, without limitation, court costs, attorneys' fees, witness fees, fines,
amounts paid in settlement or judgment and any other costs and expenses of any
nature or kind incurred in connection with any proceeding.

                   (c) The term the "corporation" shall include, in addition to
the resulting corporation, any constituent corporation (including any
constituent of a constituent) absorbed in a consolidation or merger which, if
its separate existence had continued, would have had power and authority to
indemnify its Directors, officers, and employees or agents, so that any person
who is or was a Director, officer, employee or agent of such constituent
corporation, or is or was serving at the request of such constituent corporation
as a Director, officer, employee or agent of another corporation, partnership,
joint venture, trust or other enterprise, shall stand in the same position under
the provisions of this Bylaw with respect to the resulting or surviving
corporation as he would have with respect to such constituent corporation if its
separate existence had continued.

                   (d) References to a "Director," "officer," "employee," or
"agent" of the corporation shall include, without limitation, situations where
such person is serving at the request of the corporation as a Director, officer,
employee, trustee or agent of another corporation, partnership, joint venture,
trust or other enterprise.

                   (e) References to "other enterprises" shall include employee
benefit plans; references to "fines" shall include any 


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   32
excise taxes assessed on a person with respect to an employee benefit plan; and
references to "serving at the request of the corporation" shall include any
service as a Director, officer, employee or agent of the corporation which
imposes duties on, or involves services by, such Director, officer, employee, or
agent with respect to an employee benefit plan, its participants, or
beneficiaries; and a person who acted in good faith and in a manner he
reasonably believed to be in the interest of the participants and beneficiaries
of an employee benefit plan shall be deemed to have acted in a manner "not
opposed to the best interests of the corporation" as referred to in this Bylaw.

        Section 12. Indemnification under California Law. Prior to the Record
Date, the corporation shall indemnify its officers, Directors, employees and
agents to the full extent permitted by the California General Corporation Law.


                                  ARTICLE VIII

        Section 1. Loans to Officers. The corporation may lend money to, or
guarantee any obligation of, or otherwise assist any officer or other employee
of the corporation or of its subsidiaries, including any officer or employee who
is a Director of the Corporation or its subsidiaries, whenever, in the judgment
of the Board of Directors, such loan, guarantee or assistance may reasonably be
expected to benefit the corporation. The loan, guarantee or other assistance may
be with or without interest and may be unsecured, or secured in such manner as
the Board of Directors shall approve, including, without limitation, a pledge 


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   33
of shares of stock of the corporation. Nothing in this bylaw shall be deemed to
deny, limit or restrict the powers of guaranty or warranty of the corporation at
common law or under any statute.


                                   ARTICLE IX

                               GENERAL PROVISIONS

        Section 1. Declaration of Dividends. 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. Dividend Reserve. 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 purposes 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.

        Section 3. Execution of Corporate Instruments. 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.

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   34
        Section 4. Fiscal Year. The fiscal year of the corporation shall be
fixed by resolution of the Board of Directors.

        Section 5. Corporate Seal. The Board of Directors may adopt a corporate
seal having 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.

        Section 6. Annual Report.

                   (a) Subject to the provisions of paragraph (b) of this Bylaw,
the Board of Directors shall cause an annual report to be sent to each
stockholder of the corporation not later than one hundred twenty (120) days
after the close of the corporation's fiscal year. Such report shall include a
balance sheet as of the end of such fiscal year and an income statement and
statement of changes in financial position for such fiscal year, accompanied by
any report thereon of independent accounts or, if there is no such report, the
certificate of an authorized officer of the corporation that such statements
were prepared without audit from the books and records of the corporation. When
there are more than 100 stockholders of record of the corporation's shares, as
determined by Section 605 of the California Corporations Code, additional
information as required by Section 1501(b) of the California Corporations Code
shall also be contained in such report, provided that if the corporation has a
class of securities registered under Section 12 of the 1934 Act, that Act shall
take precedence. Such report shall be sent 


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   35
to stockholders at least fifteen (15) days prior to the next annual meeting of
stockholders after the end of the fiscal year to which it relates.

                   (b) If and so long as there are fewer than 100 holders of
record of the corporation's shares, the requirement of sending of an annual
report to the stockholders of the corporation is hereby expressly waived.


                                    ARTICLE X

                                   AMENDMENTS

        Section 1. Amendments.

                   (a) Except as otherwise set forth in Section 9 of Article VII
of these Bylaws, the Bylaws may be altered or amended or new Bylaws adopted by
the affirmative vote of a majority of the voting power of all of the
then-outstanding shares of capital stock of the corporation entitled to vote
generally in the election of Directors (the "Voting Stock"). The Board of
Directors shall also have the power, if such power is conferred upon the Board
of Directors by the Certificate of Incorporation, to adopt, amend or repeal
Bylaws.

                   (b) Notwithstanding any other provisions of these Bylaws or
any provision of law which might otherwise permit a lesser vote or no vote, but
in addition to any affirmative vote of the holders of any particular class or
series of the Voting Stock required by law, the Certificate of Incorporation or
any Preferred Stock Designation (as the term is defined in the Certificate of
Incorporation), the affirmative vote of the 



                                      -33-
   36
holders of at least sixty-six and two-thirds percent (66-2/3%) of the voting
power of all of the then-outstanding shares of the Voting Stock, voting together
as a single class, shall be required to alter, amend or repeal this paragraph
(b) or Section 2 or Section 10 of Article II or Section 1 of Article III of
these Bylaws.

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   37
                            CERTIFICATE OF SECRETARY

        The undersigned, being the Secretary of Ligand Pharmaceuticals
Incorporated, a Delaware corporation, does hereby certify the foregoing to be
the Bylaws of said Corporation, as adopted by the incorporator and Directors of
the Corporation and which remain in full force and effect as of the date hereof.

        Executed at San Diego, California effective as of November 25, 1992.


                                          /s/ WILLIAM L. RESPESS
                                          ---------------------------------
                                              William L. Respess, Secretary


                                      -35-