Exhibit 3.1

                          CERTIFICATE OF INCORPORATION
                                       OF
                          IMCLONE SYSTEMS INCORPORATED

     I, H. Kenneth Fish, the incorporator hereinafter named, for the purpose of
forming a corporation pursuant to the General Corporation Law of the State of
Delaware, do make this certificate, hereby declaring and certifying that this is
my act and deed and that the facts herein stated are true;

     FIRST: The name of the corporation (the "Corporation") is IMCLONE SYSTEMS
INCORPORATED.

     SECOND: The address of the registered office of the Corporation in the
State of Delaware is 100 West 10th Street, Wilmington, County of New Castle; and
the name of its registered agent at such address is The Corporation Trust
Company.

     THIRD: The purposes of the Corporation are to engage in research and
development, production, manufacturing and distribution of products based on
genetic engineering, including but not limited to such products based on
recombinant DNA techniques and monoclonal antibody techniques of production and
to provide consulting and other services as related to the foregoing business.

     To acquire, hold, dispose of, buy, sell, underwrite, handle on commission
and otherwise deal in stocks, shares, bonds, notes and obligations of the
interests in corporations, joint-stock companies, trusts, associations, firms or
persons and all forms of public and municipal securities of this or any other
country, or any right or interest therein, and while owner thereof, to exercise
all rights, powers and privileges of ownership in the same manner and to the
same extent that an individual might;

     To acquire, hold, use, dispose of buildings, plants, factories, mills,
machinery, works and all other real and personal property, tangible or
intangible, of whatever kind and wherever situated, or any right or interest
therein for the purposes of the foregoing businesses; patent rights and
privileges, inventions, formulae, trademarks and names, secret processes or any
right or interest therein; as a going business or otherwise, all or any part of
the assets of any corporation,


<PAGE>

joint-stock company, trust, association, firm or person, and in such cases to
assume all or any part of its or his liabilities.

     To conduct any other lawful act or activity for which corporations may be
organized under the General Corporation Law of Delaware.

     FOURTH: The total number of shares of capital stock which the Corporation
shall have authority to issue is one million (1,000,000) shares of common stock
with a par value of five cents ($0.05) per share.

     FIFTH: The name and the mailing address of the incorporator is as follows:

                  NAME         MAILING ADDRESS
                  ----         ---------------

          H. Kenneth Fish      Foley, Hoag & Eliot
                               One Post Office Square
                               Boston, Massachusetts 02109

     SIXTH: The names and the mailing addresses of the initial directors are as
follows:

          Harlan Waxsel        101 West 81st Street
                               Unit 712
                               New York, New York

          Jack Waxsel          260 Hornwood Drive
                               Dayton, Ohio 45405

          Salvatore Vernace    Pomona Professional Plaza
                               Route 45
                               Pomona, New York 10970

     SEVENTH: The original by-laws of the Corporation shall be adopted by the
incorporator Thereafter, the power to make, alter, or repeal the by-laws, and to
adopt any new by-law, shall be vested in the board of directors of the
Corporation.

     EIGHTH: Elections of directors need not be by written ballot unless the
by-laws of the corporation shall so provide.

<PAGE>

     NINTH: Each person who at any time is, or shall have been, a director or
officer of the Corporation, and is threatened to be or is made a party to any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that he is, or
was, a director or officer of the Corporation, or served at the request of the
Corporation as a director, officer, employee, trustee, or agent of another
corporation, partnership, joint venture, trust or other enterprise, shall be
indemnified against expenses (including attorneys' fees), judgments, fines and
amounts paid in settlement actually and reasonably incurred by him in connection
with any such action, suit or proceeding to the full extent provided by the
General Corporation Law of the State of Delaware. The foregoing Jack Waxsel
right of indemnification shall in no way be exclusive of any other rights of
indemnification to which any such director, officer, employee, or agent may be
entitled, under any by-law, agreement, vote of stockholders or disinterested
directors or otherwise.

     TENTH: Whenever a compromise or arrangement is proposed between this
Corporation and its creditors or any class of them and/or between this
Corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of this Corporation or of any creditor or stockholder thereof, or on the
application of any receiver or receivers appointed for this Corporation under
the provisions of Section 291 of Title 8 of the Delaware Code or on the
application of trustees in dissolution or of any receiver or receivers appointed
for this Corporation under the provisions of Section 279 of Title 8 of the
Delaware Code, order a meeting of the creditors or class of creditors, and/or of
the stockholders or class of stockholders of this Corporation, as the case may
be, to be summoned in such manner as said court directs. If a majority in number
representing three-fourths in value of the creditors or class of creditors
and/or of the stockholders or class of stockholders of this Corporation, as the
case may be, agree to any compromise or arrangement and to any reorganization of
this Corporation as consequence of such compromise or arrangement, the said
compromise or arrangement and the said reorganization shall, if sanctioned by
the court to which the said application has been made, be binding on all the
creditors or class of creditors, and/or on all the stockholders or class of
stockholders of this Corporation, as the case may be, and also on this
Corporation.

<PAGE>

     IN WITNESS WHEREOF, I have hereunto set my hand and seal this 24th day of
April, 1984.

[Seal]                                       /s/ H. Kenneth Fish
                                             -----------------------------
                                             H. Kenneth Fish, Incorporator

<PAGE>

               CERTIFICATE OF CORRECTION FILED TO CORRECT A
               CERTAIN ERROR IN THE CERTIFICATE OF INCORPORATION
               OF IMCLONE SYSTEMS INCORPORATED FILED IN THE
               OFFICE OF THE SECRETARY OF STATE OF DELAWARE ON
               APRIL 26, 1984, AND RECORDED IN THE OFFICE OF THE
               RECORDER OF DEEDS FOR NEW CASTLE COUNTY, DELAWARE,
               ON APRIL 26, 1984

     IMCLONE SYSTEMS INCORPORATED, a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware,

     DOES HEREBY CERTIFY:

     1. The name of the corporation is IMCLONE SYSTEMS INCORPORATED.

     2. That a Certificate of Incorporation was filed by the Secretary of State
of Delaware on April 26, 1984 and recorded in the office of the Recorder of
Deeds of New Castle County on April 26, 1984 and that said certificate requires
correction as permitted by subsection (F) of section 103 of The General
Corporation Law of the State of Delaware.

     3. The inaccuracy or defect of said certificate to be corrected is as
follows:

          The surname of two of the initial directors referred to in paragraph
     SIXTH is Waksal rather than Waxsel.

     4. Paragraph SIXTH of the certificate is corrected to read as follows:

     SIXTH: The names and the mailing addresses of the initial directors are as
follows:

          Harlan Waksal                 101 West 81st Street
                                        Unit 712
                                        New York, New York

          Jack Waksal                   260 Hornwood Drive
                                        Dayton, Ohio 45405

          Salvatore Vernace             Pomona Professional Plaza
                                        Route 45
                                        Pomona, New York 10970


<PAGE>

     IN WITNESS WHEREOF, said IMCLONE SYSTEMS INCORPORATED has caused this
certificate to be signed by Jack Waksal and Salvatore Vernace, a majority of its
Directors, 26th day of April, 1984.

                                           IMCLONE SYSTEMS INCORPORATED

                                           /s/ Salvatore Vernace
                                           -------------------------------------
Michael A. Stetl Notary Public
in and for the State of Ohio               /s/ Jack Waksal
                                           -------------------------------------
My Commission expires Dec. 4, 1985
/s/ Michael A. Stetl
------------------------------------
5/30/84

<PAGE>

                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION

     ImClone Systems Incorporated, a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware, DOES
HEREBY CERTIFY:

     FIRST: That the Board of Directors of said Corporation, by the unanimous
written consent of its members dated September 13, 1984 filed with the minutes
of the Board, adopted a resolution proposing and declaring advisable the
following amendment to the Certificate of Incorporation of said Corporation:

     RESOLVED, that the Certificate of Incorporation of ImClone Systems
     Incorporated be amended by changing the FOURTH Article so that as amended
     said Article shall be and read as follows: "The total number of shares of
     capital stock which the Corporation shall have authority to issue is two
     million (2,000,000) shares of common stock with a par value of five cents
     ($0.05) per share.

     SECOND: That in lieu of a meeting and vote of stockholders, the
stockholders have given written consent to said amendment in accordance with the
provisions of section 228 of the General Corporation Law of the State of
Delaware and written notice of the adoption of the amendment has been given as
provided in section 228 of the General Corporation Law of the State of Delaware
to every stockholder entitled to such notice.

     THIRD: That the aforesaid amendment was duly adopted in accordance with the
applicable provisions of sections 242 and 228 of the General Corporation Law of
the State of Delaware.

<PAGE>

     IN WITNESS WHEREOF, said ImClone Systems Incorporated has caused this
certificate to be signed by Harlan Waksal, its President, and attested by H.
Kenneth Fish, its Secretary, this 29th day of September, 1984

                                        IMCLONE SYSTEMS INCORPORATED

                                        By /s/ Harlan W. Waksal M.D.
                                        --------------------------------------
                                           Harlan Waksal, its President
ATTEST:

By /s/ H. Kenneth Fish
   --------------------------------
   H. Kenneth Fish, Secretary


<PAGE>

                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION

     ImClone Systems Incorporated, a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware, DOES
HEREBY CERTIFY:

     FIRST: That the Board of Directors of said Corporation, by the unanimous
written consent of its members dated May 20, 1986 filed with the minutes of the
Board, adopted a resolution proposing and declaring advisable the following
amendment to the Certificate of Incorporation of said Corporation.

     RESOLVED, that the Certificate of Incorporation of ImClone Systems
     Incorporated be amended by changing the FOURTH Article so that as amended
     said Article shall be and read as follows: "The total number of shares of
     capital stock which the Corporation shall have authority to issue is seven
     million (7,000,000) shares of common stock with a par value of five cents
     ($0.05) per share."

     SECOND: That in lieu of a meeting and vote of stockholders, the
stockholders have given written consent to said amendment in accordance with the
provisions of section 228 of the General Corporation Law of the State of
Delaware and written notice of the adoption of the amendment has been given as
provided in section 228 of the General Corporation Law of the State of Delaware
to every stockholder entitled to such notice.

     THIRD: That the aforesaid amendment was duly adopted in accordance with the
applicable provisions of sections 242 and 228 of the General Corporation Law of
the State of Delaware.


<PAGE>

     IN WITNESS WHEREOF, said ImClone Systems Incorporated has caused this
certificate to be signed by Harlan Waksal, its President, and attested by John
Landes, its Secretary, this 16th day of June 1986.

                                        IMCLONE SYSTEMS INCORPORATED

                                        By /s/ Harlan W. Waksal M.D.
                                        --------------------------------------
                                           Harlan Waksal, its President

ATTEST.

By /s/ John Landes
---------------------------------
   John Landes, Secretary

<PAGE>

                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                          IMCLONE SYSTEMS INCORPORATED

     The undersigned hereby certifies that the following amendment to the
Certificate of Incorporation of ImClone Systems Incorporated (the "Corporation")
has been duly adopted in accordance with the provisions of Sections 242 and 228
of the General Corporation Law of Delaware and that, pursuant to said Section
228, written notice of said adoption has been provided to those stockholders of
the Corporation who did not consent in writing to such adoption:

     That the Certificate of Incorporation of the Corporation be, and it hereby
is, amended by addition thereto of a new Article ELEVENTH as follows:

     ELEVENTH: To the maximum extent permitted by the General Corporation Law of
     the State of Delaware, as the same exists or may hereafter be amended, no
     director of this Corporation shall be personally liable to the Corporation
     or to any of its stockholders for monetary damages arising out of such
     director's breach of fiduciary duty as a director of the Corporation.

     IN WITNESS WHEREOF, said ImClone Systems Incorporated has caused this
certificate to be signed by Harlan Waksal, its President, and attested by John
Landes, its Secretary, this 27 day of May, 1987.

                                        
ATTEST:                                 IMCLONE SYSTEMS INCORPORATED


/s/ John B. Landes                      By /s/ Harlan W. Waksal M.D.
-------------------------               --------------------------------------
John B. Landes, Secretary                  Harlan Waksal, its President

<PAGE>

                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                          IMCLONE SYSTEMS INCORPORATED

                           Pursuant to Section 242 of
                      The Delaware General Corporation Law

     We, Harlan W. Waksal, Executive Vice President, and John B. Landes,
Secretary, respectively, of ImClone Systems Incorporated, a corporation
organized and existing under and by virtue of the Delaware General Corporation
Law (the "Corporation"), do hereby certify as follows:

     FIRST: That the Board of Directors of the Corporation duly adopted the
following amendment to the Certificate of Incorporation of the Corporation,
proposing and declaring such amendment to be advisable and directing that such
amendment be submitted to the stockholders of the Corporation for their
approval. The Amendment is that Article NINTH of the Certificate of
Incorporation of the Corporation be amended to read in its entirety as follows:

     "NINTH (a) Each person who was or is made a party or is threatened to be
made a party to or is involved in any action, suit or proceeding, whether civil,
criminal, administrative or investigative (hereinafter a "proceeding"), by
reason of the fact that he or she, or a person of whom he or she is the legal
representative, is or was a director or officer of the Corporation or is or was
serving at the request of the Corporation as a director, officer, employee or
agent of another corporation or of a partnership, joint venture, trust or other
enterprise, including service with respect to employee benefit plans, whether
the basis of such proceeding is alleged action in an official capacity as a
director, officer, employee or agent or in any other capacity while serving as a
director, officer, employee or agent, shall be indemnified and held harmless by
the Corporation to the fullest extent authorized by the Delaware General
Corporation Law, as the same exists or may hereafter be amended, against all
expense, liability and loss (including attorneys' fees, judgments, fines, excise
taxes or penalties under the Employee Retirement Income Security Act and amounts
paid or to be paid in settlement) reasonably incurred or suffered by such person
in connection therewith, and such indemnification shall continue as to a person
who has ceased to be a director, officer, employee or agent and shall inure to
the benefit of his or her heirs, executors and administrators, provided,
however, that, except as provided in paragraph (b) hereof, the Corporation shall
indemnify any such person seeking indemnification in connection with a
proceeding (or part thereof) initiated by such person only if such proceeding
(or part thereof) was authorized by the board of directors of the Corporation.
The right to indemnification conferred in this Article NINTH shall be a contract
right and shall include the


<PAGE>

right to be paid by the Corporation the expenses incurred in defending any such
proceeding in advance of its final disposition; provided, however, that, if the
Delaware General Corporation Law requires, the payment of such expenses incurred
by a director or officer in his or her capacity as a director or officer (and
not in any other capacity as a director or officer, including, without
limitation, service to an employee benefit plan) in advance of the final
disposition of a proceeding, shall be made only upon delivery to the Corporation
of an undertaking, by or on behalf of such director or officer, to repay all
amounts so advanced if it shall ultimately be determined that such director or
officer is not entitled to be indemnified under this Article NINTH or otherwise.
The provisions of this paragraph (a) shall apply to any member of any Committee
appointed by the Board of Directors as fully as though such person shall have
been an officer or director of the Corporation. The Corporation may, by action
of its Board of Directors, provide indemnification to employees and agents of
the Corporation with the same scope and effect as the foregoing indemnification
of directors and officers.

     (b) If a claim under paragraph (a) of this Article is not paid in full by
the Corporation within thirty days after a written claim has been received by
the Corporation, the claimant may at any time thereafter bring suit against the
Corporation to recover the unpaid amount of the claim and, if successful in
whole or in part, the claimant shall be entitled to be paid also the expense of
prosecuting such claim. It shall be a defense to any such action (other than an
action brought to enforce a claim for expenses incurred in defending any
proceeding in advance of its final disposition where the required undertaking,
if any is required, has been tendered to the Corporation) that the claimant has
not met the standards of conduct which make it permissible under the Delaware
General Corporation Law for the Corporation to indemnify the claimant for the
amount claimed, but the burden of proving such defense shall be on the
Corporation. 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 or she 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 the claimant has not met the applicable standard of
conduct.

     (c) The Corporation may maintain insurance, at its expense, to protect
itself and any director, officer, employee or agent of the Corporation or
another corporation, partnership, joint venture, trust or other enterprise
against any such expense, liability, or loss, whether or not the Corporation
would have the power to indemnify such person against such expense, liability or
loss under the Delaware General Corporation Law.

     (d) The provisions of this Article NINTH shall be in addition to and not in
limitation of any other rights, indemnities, or limitations of liability to
which any director or officer may be entitled, as a matter of law or under any
By-Law, agreement, vote of stockholders or otherwise."

<PAGE>

     SECOND: That a special meeting of the stockholders of said Corporation was
duly called and held, upon notice in accordance with Section 222 of the Delaware
General Corporation Law, at which meeting the necessary number of shares as
required by statute were voted in favor of the Amendment.

     THIRD: That the Amendment set forth in Article FIRST hereof was duly
adopted in accordance with the applicable provisions of Section 242 of the
Delaware General Corporation law.

     IN WITNESS WHEREOF, we have signed this certificate this 28 day of March
1988.

                                             /s/ Harlan W. Waksal
                                             ------------------------------
                                             Harlan W. Waksal
                                             Executive Vice President

Attest

/s/ John B. Landes
------------------------
John B Landes
Secretary

<PAGE>

                            CERTIFICATE 0F AMENDMENT
                                       TO
                          CERTIFICATE OF INCORPORATION
                                       OF
                          IMCLONE SYSTEMS INCORPORATED

                under section 242 or the General Corporation law
                            of the State of Delaware


The undersigned, being the Executive Vice President of IMCLONE SYSTEMS
INCORPORATED, a Delaware corporation (the "Corporation") DOES HEREBY CERTIFY as
follows:

     FIRST: The Certificate of Incorporation of the Corporation is hereby
amended by deleting Article FOURTH in its entirety and inserting the following
in lieu thereof:

          "FOURTH: (a) the total number of shares of capital stock which the
Corporation shall have the authority to issue shall be 16,000,000 shares, of
which 15,000,000 shares shall be Common Stock with a par value of one cent
($.0l) per share, and 1,000,000 shares shall be Preferred Stock with a par value
of one dollar ($1.00) per share.

     A statement of the designations of the authorized classes of stock or of
any series thereof, and the voting powers, full or limited, or no voting powers,
preferences and relative, participating, optional or other special rights, and
qualifications, limitations or restrictions thereof, or of the authority of the
Board of Directors to fix by resolution or resolutions such designations and
other terms not fixed by the Certificate of Incorporation, is as follows:

          1. The Board of Directors is authorized, subject to the limitations
     prescribed by law and in accordance with the provisions hereof, to provide
     for the issuance or Preferred Stock in one or more series, from time to
     time and, by filing a certificate of designations pursuant to the General
     Corporation Law, to establish the number of shares to be included in each
     such series, and to fix the designation, voting powers, full or limited, or
     no voting powers, preferences, and relative, participating, optional or
     other special rights, and qualifications, limitations or restrictions of
     the shares of each such series. The authority of the Board or Directors
     with respect to each such series shall include, but not be limited to, the
     determination or fixing of the following:

               (i) The distinctive designation and number of shares comprising
          such series;

<PAGE>

               (ii) The dividend rate of such series, the conditions and time
          upon which such dividends shall be payable, the relation which such
          dividends shall bear to the dividends payable on any other class or
          classes of stock or series thereof, or any other series of the same
          class, and whether such dividends shall be cumulative or
          non-cumulative;

               (iii) The conditions upon which the shares of such series shall
          be subject to redemption by the Corporation and the times, prices and
          other terms and provisions upon which the shares of the series may be
          redeemed;

               (iv) Whether or not the shares of the series shall be subject to
          the operation of a retirement or sinking fund to be applied to the
          purchase or redemption of such shares and, if such retirement or
          sinking fund be established, the annual amount thereof and the terms
          and provisions relative to the operation thereof;

               (v) Whether or not the shares of the series shall be convertible
          into or exchangeable for shares or any other class or classes, with or
          without par value, or of any other series of the same class, and, it
          provision is made for conversion or exchange, the times, prices,
          rates, adjustments, and other terms and conditions of such conversion
          or exchange;

               (vi) Whether or not the shares of the series shall have voting
          rights, in addition to the voting rights provided by law, and, if so,
          subject to the limitation hereinafter set forth, the terms of such
          voting rights;

               (vii) The rights of the shares of the series in the event of
          voluntary or involuntary liquidation, dissolution, or upon the
          distribution of assets of the Corporation;

               (viii) Any other powers, preferences and relative participating,
          optional or other special rights, and qualifications, limitations or
          restrictions thereof, of the shares of such series, as the Board of
          Directors may deem advisable and as shall not be inconsistent with the
          provisions of this Certificate of Incorporation.

     2. The holders of shares of the Preferred Stock of each series shall be
entitled to receive, when and as declared by the Board of Directors, out of
funds legally available for the payment of dividends, dividends at the rates
fixed by the Board of Directors for such series, and no more, before any
dividends, other than dividends payable in Common Stock, shall be declared and
paid, or set apart for payment, on the Common Stock with respect to the same
dividend period.

     3. The holders of shares of the Preferred Stock of each series shall be
entitled upon liquidation or dissolution or upon the distribution of the assets
of the corporation to such preferences as provided in the resolution or
resolutions creating such series of Preferred Stock, and no more, before any
distribution or the assets of the Corporation shall be made to the holders

<PAGE>

of shares of the Common Stock. Whenever the holders of shares of the Preferred
Stock shall have been paid the full amounts to which they shall be entitled, the
holders of shares of the Common Stock shall be entitled to share ratably in all
assets of the corporation remaining.

     4. At all meetings of the stockholders of the corporation, the holders of
shares of the Common Stock shall be entitled to one vote for each share of
Common Stock held by them. Except as otherwise provided by a resolution or
resolutions of the Board of Directors creating any series of Preferred Stock or
by the Delaware General Corporation Law, the holders of shares of the Common
Stock issued and outstanding shall have and possess the exclusive right to
notice of stockholders' meetings and the exclusive power to vote.

     (b) A director shall be fully protected in relying in good faith upon the
books of account of the Corporation or statements prepared by any of its
officials as to the value and amount of the assets, liabilities and/or net
profits of the Corporation, or any other facts pertinent to the existence and
amount of surplus or other funds from which dividends might properly be declared
and paid.

     (c) The Corporation shall be entitled to treat the person in whose name any
share, right or option is registered as the owner thereof, for all purposes, and
shall not be bound to recognize any equitable or other claim to or interest in
such share, right or option on the part of any other person, whether or not the
Corporation shall have notice thereof, save as may be expressly provided by the
laws of the state of Delaware. 

     SECOND: That such amendment was duly adopted by the Board of Directors of
the Corporation and by the Stockholders of the Corporation in accordance with
Section 242 of the General Corporation Law of the State of Delaware.

     IN WITNESS WHEREOF, this Certificate of Amendment to this Certificate of
Incorporation of the Corporation has been signed, and the statements made herein
affirmed as true under the penalties of perjury, this l2th day of June, 1991.


                                             /s/ Harlan W. Waksal
                                             -----------------------------
                                             Harlan W. Waksal
                                             Executive Vice President

ATTEST: /s/ John B. Landes
        --------------------------
        John B. Landes

<PAGE>

                            CERTIFICATE OF AMENDMENT
                                       To
                          CERTIFICATE OF INCORPORATION
                                       0F
                          IMCLONE SYSTEMS INCORPORATED
                Under Section 242 of the General Corporation Law
                            of the State of Delaware

     The undersigned, being the Executive Vice President of IMCLONE SYSTEMS
INCORPORATED, a Delaware corporation (the "Corporation") DOES HEREBY CERTIFY as
follows:

     FIRST: The Certificate of Incorporation of the Corporation is hereby
amended by deleting the first paragraph of Article FOURTH in its entirety and
inserting the following in lieu thereof:

          "FORTH: (a) The total number of shares of capital stock which the
     corporation shall have the authority to issue in thirty million
     (30,000,000) shares or Common Stock with a par Value of one tenth of one
     cent ($.001) per share and four million (4,000,000} shares of Preferred
     Stock with par value of one dollar ($1.00) per share."

     SECOND: The Certificate of Incorporation of the Corporation is further
amended to add a new Article TWELFTH to read as follows;

          "TWELFTH: Each outstanding share of Common Stock, par value $.01 per
     share, is hereby re-classified and changed into one and one-half shares of
     Common Stock, par value $.00l per share, and upon the filing of this
     amendment to the Certificate of Incorporation, each outstanding share of
     Common Stock, par value $.01 per share, shall be split up and converted
     into one and one-half shares of Common Stock, par value $.00l per share."

     THIRD: That such amendment was duly adopted by the Board of Directors of
the Corporation and by the Stockholders of the corporation in accordance with
Section 242 of the General Corporation Law of the State of Delaware.

<PAGE>

     IN WITNESS HEREOF, this Certificate of Amendment to the Certificate of
Incorporation of the Corporation has been signed, and the statements made herein
affirmed as true under the penalties of perjury, this 16th day of' September,
1991.

                                        /s/ Harlan W. Waksal
                                        --------------------------
                                        Harlan W. Waksal,
                                        Executive Vice President

ATTEST: /s/ John B. Landes
        ----------------------------
        John B. Landes, Secretary

<PAGE>

                            CERTIFICATE OF AMENDMENT
                                       TO
                          CERTIFICATE OF INCORPORATION
                                       OF
                          IMCLONE SYSTEMS INCORPORATED

                Under Section 242 of the General Corporation Law
                            of the State of Delaware

The  undersigned,   being  the  Executive  Vice  President  of  IMCLONE  SYSTEMS
INCORPORATED,  a Delaware corporation (the "Corporation") DOES HEREBY CERTIFY as
follows:

     FIRST: The Certificate of Incorporation of the Corporation is hereby
amended so that Article FOURTH (a) shall read in its entirety as follows:

     "FOURTH: (a) The total number of shares of capital stock which the
Corporation shall have the authority to issue is forty-five million (45,000,000)
shares of Common Stock with a par value of one tenth of one cent ($.001) per
share and four million (4,000,000) shares of Preferred Stock with a par value of
one dollar ($1.00) per share."

     SECOND: That such amendment was duly adopted by the Board of Directors of
the Corporation and by the Stockholders of the Corporation in accordance with
Section 242 of the General Corporation Law of the State of Delaware.

     IN WITNESS WHEREOF, this Certificate of Amendment to the Certificate of
Incorporation of the Corporation has been signed, and the statements hereto
affirmed as true under the penalties of perjury, this 18 day of July, 1997.

                                        /s/ Harlan W. Waksal
                                        -------------------------------
                                        Harlan W. Waksal
                                        Executive Vice President


Attest: /s/ John B. Landes
        --------------------------
        John B. Landes