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                                                                    Exhibit 99.1

                          IMCLONE SYSTEMS INCORPORATED

                 1996 INCENTIVE STOCK OPTION PLAN, AS AMENDED(1)


                                   ARTICLE 1
                                 PURPOSE OF PLAN

         Section 1.01. General Purpose. The purpose of this Incentive Stock
Option Plan (the "PLAN") is to promote the interests of ImClone Systems
Incorporated, and any subsidiaries of such company, as from time to time may be
formed or acquired (collectively, the "COMPANY"), by affording key executives
and employees an opportunity to acquire a proprietary interest in the Company
pursuant to stock options issued by the Company, and thus to create in such
employees increased personal interest in its continued success.

         Section 1.02. Statutory Stock Option. Options granted under the Plan
are intended to be "incentive stock options" to which Section 422 of the
Internal Revenue Code of 1986, as amended (the "CODE"), applies.



                                   ARTICLE 2
                             SHARES SUBJECT TO PLAN

         Section 2.01. Descriptions Of Shares. Subject to Article 7 hereof, the
stock to which the Plan applies is shares of the Company's common stock, $.001
par value ("COMMON STOCK"), either authorized but unissued or Treasury shares.
The number of shares of Common Stock to be issued or sold pursuant to options
granted hereunder shall not exceed 11,000,000 shares; provided, that such number
shall be reduced by the number of shares which have been sold under, or may be
sold pursuant to options granted from time to time under, the Company's 1996
Non-Qualified Stock Option Plan (the "Non-Qualified Plan"), to the same extent
as if such sales had been made or options had been granted pursuant to this
Plan.

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         (1) This plan was adopted by the board on February 25, 1996 and
approved by the stockholders on June 3, 1996; it was amended by the Board on
April 3, 1997 and such amendments were ratified by the stockholders on June 3,
1997; it was amended by the Board on March 29, 1999 subject to shareholder
approval and such amendments were ratified by the stockholders on May 24, 1999;
it was amended by the Board on December 16, 1999; it was amended by the Board on
April 14, 2000 and such amendments were ratified by the stockholders on May 31,
2000; it was amended by the Board on September 18, 2000; it was amended by the
Board on November 15, 2001.
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         Section 2.02. Restoration Of Unpurchased Shares. Any shares subject to
an option granted hereunder or under the Non-Qualified Plan that, for any
reason, expires or is terminated unexercised as to such shares may again be
subject to an option to be granted hereunder.


                                    ARTICLE 3
                     ADMINISTRATION; COMMITTEES; AMENDMENTS

         Section 3.01. Administration. The Plan shall be administered by any of
the Compensation Committee, the Stock Option Committee (which is a subcommittee
of the Compensation Committee) (collectively, the "COMMITTEES") or the Company's
Board of Directors (the "BOARD"). The Committees shall be comprised of not less
than two persons who shall be appointed by the Board from among the members of
the Board. Members of the Committees shall not be eligible to become
participants under the Plan while they are members of the Committees or for a
period of three months thereafter.

         Section 3.02. Duration; Removal; Etc.. The members of the Committees
shall serve at the pleasure of the Board, which shall have the power at all
times to remove members from the Committees or to add members thereto. Vacancies
in the Committees, however caused, shall be filled by action of the Board.

         Section 3.03. Meetings; Actions Of Committees. Each of the Committees
and the Board may select one of its members as its Chairman and shall hold its
meetings at such times and places as it may determine. All decisions or
determinations of each of the Committees and the Board shall be made by the
majority vote or decision of all of its members, whether present at a meeting or
not; provided, however, that any decision or determination reduced to writing
and signed by all of the members shall be as fully effective as if it had been
made at a meeting duly called and held. Each of the Committees and the Board may
make such rules and regulations for the conduct of its business not inconsistent
herewith, as it may deem advisable.

         Section 3.04. Interpretation. The interpretation and construction by
any of the Committees or the Board of the provisions of the Plan or of the
options granted hereunder shall be final, unless in the case of the Committees
otherwise determined by the Board. No member of the Board or of the Committees
shall be liable for any action taken or determination made in good faith.

         Section 3.05. Amendments Or Discontinuation. The Board may make such
amendments, changes, and additions to the Plan, or may discontinue and terminate
the Plan, as it may deem advisable from time to time; provided, however, that no
action shall affect or impair any options theretofore granted under the Plan,
and provided, further, however, that the affirmative vote of the owners of a
majority of the outstanding shares of Common Stock present at a meeting in
person or by proxy and entitled to vote at the meeting shall be

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necessary to effect any amendment to the Plan which would (a) increase the
number of shares of Common Stock subject to options granted under the Plan, or
(b) authorize the granting of options at a price below the minimum price
established by Section 5.03 hereof.


                                    ARTICLE 4
                  PARTICIPANTS; MAXIMUM GRANT; DURATION OF PLAN

         Section 4.01. Eligibility And Participation. Options shall be granted
only to persons ("PARTICIPANTS") who at the time of granting are key executives
or key employees of the Company. Subject to the provisions of Section 4.03
hereof, the Committees or the Board shall determine the key executives and key
employees to be granted options hereunder, the number of shares of Common Stock
subject to such options, the exercise prices of options, the terms thereof and
any other provisions not inconsistent with the Plan.

         Section 4.02. Guidelines For Participation. In selecting Participants
and determining the numbers of shares of Common Stock for which options are to
be granted the Committees or the Board shall consult with officers and directors
of the Company, and shall take into account the duties of the respective
employees, their present and potential contributions to the success of the
Company, and such other factors as any of the Committees or the Board shall deem
relevant.

         Section 4.03. Maximum Grant. Notwithstanding anything to the contrary
in the Plan, options granted to a Participant in any calendar year (under all
plans, including the Plan, providing for the grant of incentive stock options of
the Company and its parent and subsidiaries) in excess of the limitations of
Section 422(d) of the Code shall not be considered Incentive Stock Options
granted under this Plan and shall be deemed to be options granted under the
Non-Qualified Plan.

         Section 4.04. Duration Of Plan. All options under the Plan shall be
granted within ten years from the date the Plan is adopted, or the date the Plan
is approved by the shareholders of the Company, whichever is earlier.


                                   ARTICLE 5
                         TERMS AND CONDITIONS OF OPTIONS

         Section 5.01. Individual Stock Option Agreement. All stock options
granted pursuant to the Plan shall be evidenced by stock option agreements or
notices ("STOCK OPTION AGREEMENTS"), which need not be identical, in such form
as any of the Committees or the Board shall from time to time approve, subject
to the terms of the Plan which may, but need not, be executed or acknowledged by
a Participant.

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         Section 5.02. Number Of Shares. Each Stock Option Agreement shall
state the total number of shares of Common Stock with respect to which the
option is granted, the terms and conditions of the option, and the exercise
price or prices thereof, it being understood that any of the Committees or the
Board shall have authority to prescribe in any Stock Option Agreement that the
option evidenced thereby may be exercisable in full or in part, as to any number
of shares subject thereto, at any time or from time to time during the term of
the option, or in such installments at such times during said term as any of the
Committees or the Board may determine; provided that no option granted pursuant
to the Plan shall be exercisable after the expiration of ten years from the date
such option is granted. A previously granted incentive stock option shall be
treated as outstanding until it is exercised in full or expires by reason of the
lapse of time. Except as otherwise provided in any Stock Option Agreement, an
option may be exercised at any time or from time to time during the term of the
option as to any or all full (but no fractional) shares which have become
purchasable under such option. Any of the Committees or the Board shall have the
right to accelerate, in whole or in part, from time to time, conditionally or
unconditionally, the right to exercise any option granted hereunder.

         Section 5.03. Option Price. The price at which the shares of Common
Stock subject to each option granted under this Plan may be purchased (the
"OPTION PRICE" or "EXERCISE PRICE") shall be determined by any of the Committees
or the Board, which shall have authority at the time the option is granted to
prescribe in any Stock Option Agreement that the price per share, with the
passage of pre-determined periods of time, shall increase from the original
price to higher prices, but in no case shall the original exercise price of any
option be less than 100% of the fair market value of such shares on the date the
option is granted, as determined by any of the Committees or the Board in
accordance with applicable Treasury Regulations. Notwithstanding anything
contained to the contrary herein, no option shall be granted to any employee
who, at the time the option is granted, owns more than 10% of the total combined
voting power of all classes of stock of the Company or of its parent or
subsidiary unless, at the time option is granted, the exercise price of the
option is at least 110% of the fair market value of the shares of Common Stock
subject to the option and such option by its terms is not exercisable after the
expiration of five years from the date such option is granted. For purposes of
determining the ownership of stock of the Company, the rules of Section 424(d)
of the Code shall be applied.

         Section 5.04. Method Of Exercising Option; Full Payment. Subject to
Section 6.01 and 6.02 hereof, options granted pursuant to the Plan may be
exercised only if the Participant was, at all times during the period beginning
on the date the option was granted and ending on the date of such exercise, an
employee of the Company, a parent or subsidiary of the Company, or a corporation
or a parent or subsidiary of such corporation issuing or assuming a stock option
in respect of such option in a transaction to which Section 424(a) of the Code
applies. Options shall be exercised by written notice to the Company,

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addressed to the Company at its principal place of business. Such notice shall
state the Participant's election to exercise the option and the number of shares
of Common Stock in respect of which it is being exercised, and shall be signed
by the Participant so exercising the option. Such notice shall be accompanied by
(a) payment of the full purchase price of such shares, which payment shall be in
cash, by check or in stock of the Company that has been owned by the participant
for at least six months, or notes of the Company or, as agreed to by the Board,
other consideration; and (b) such written representations and other documents as
may be desirable, in the opinion of the Company's legal counsel, for purposes of
compliance with state or Federal securities or other laws. In the case of
payment made in stock of the Company, the stock shall be valued at its Fair
Market Value (as hereinafter defined) on the last business day prior to the date
of exercise. The term "FAIR MARKET VALUE" for the Common Stock on any particular
date shall mean the last reported sale price of the Common Stock on the
principal market on which the Common Stock trades on such date or, if no trades
of Common Stock are made or reported on such date, then on the next preceding
date on which the Common Stock traded. The Company shall deliver a certificate
or certificates representing shares of Common Stock purchased pursuant to such
notice to the purchaser as soon as practicable after receipt of such notice,
subject to Article VIII hereof. Any of the Committees or the Board may amend an
already outstanding Stock Option Agreement to add a provision permitted by
clause (a) of this Section 5.04, and no such amendment, by itself, shall be
deemed to constitute the grant of a new option for purposes of this Plan;
provided that this sentence shall not be determinative of whether any such
amendment constitutes a new grant for purposes of qualification as an Incentive
Stock Option.

         Section 5.05. Rights As A Shareholder. No Participant shall have any
rights as a shareholder with respect to shares of Common Stock subject to an
option granted under the Plan until the date of the issuance to such Participant
of stock certificates in respect of such shares. No adjustment shall be made for
dividends or other rights for which the record date is prior to the date such
stock certificate is issued.

         Section 5.06. Other Provisions. Stock Option Agreements entered into
pursuant to the Plan may contain such other provisions (not inconsistent with
the Plan) as any of the Committees or the Board may deem necessary or desirable,
including, but not limited to, covenants on the part of the Participant not to
compete, not to sell Common Stock obtained from the exercise of options for
specified periods of time, and remedies available to the Company in the event of
the breach of any such covenant.

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                                   ARTICLE 6
                   TERMINATION OF EMPLOYMENT; TRANSFERABILITY

         Section 6.01. Termination Of Employment. Except as otherwise provided
in connection with the grant of any option or the termination of any
Participant, in the event a Participant's employment or service with the Company
is terminated other than by reason of death or disability, (a) with respect to
options granted prior to December 16, 1999, the right to exercise any
unexercised option or unexercised portion of any option (regardless of whether
or not vested) granted under the Plan shall terminate on the date of termination
of the relationship between the Participant and the Company and, (b) with
respect to options granted on or after December 16, 1999, (i) the right to
exercise any unvested option or unvested portion of any option granted under the
Plan shall terminate on the date of termination of the relationship between the
Participant and the Company and (ii) the right to exercise any option or portion
of any option granted under the Plan which is vested as of the date of
termination of employment or service shall terminate upon the earlier of (A) the
thirtieth day following such termination of employment or service or (B) the
date such option or portion of an option would have expired had it not been for
the termination of employment or service. The option may not be exercised after
its expiration in accordance with the foregoing terms, and the shares of Common
Stock subject to the unexercised portion of such option may again be subject to
new options under the Plan.

         Section 6.02. Death Or Disability Of Participant. Except as otherwise
permitted in connection with the grant of any option or the death or disability
of a Participant, in the event a Participant dies or is disabled while in the
employ of the Company or of a parent or subsidiary of the Company, any options
theretofore granted to him shall be exercisable only within the next 12 months
immediately succeeding such death or disability and then only in the case of
death (a) by the person or persons to whom the Participant's rights under the
option shall pass by will or the laws of descent and distribution, and, in the
case of disability, by such Participant or his legal representative, and (b) if
and to the extent that he was entitled to exercise the option at the date of his
death.

         Section 6.03. Transferability. Options granted to a Participant under
the Plan shall not be transferable otherwise than by will, by the laws of
descent and distribution, or (if authorized in the applicable Stock Option
Agreement) pursuant to a qualified domestic relations order ("QDRO") as defined
by the Internal Revenue Code of 1986, as amended, or Title I of the Employee
Retirement Income Security Act of 1974, as amended, or the rules thereunder.
During the Participant's lifetime, options shall be exercised only by such
Participant, such Participant's guardian or legal representative, or (if
authorized in the applicable Stock Option Agreement) such Participant's
transferee pursuant to a QDRO.

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                                   ARTICLE 7
                               CAPITAL ADJUSTMENTS

         Section 7.01. Capital Adjustments. If any change is made in the shares
of Common Stock subject to the Plan or subject to any option granted under the
Plan (through merger, consolidation, reorganization, recapitalization, stock
dividend, split-up, combination of shares, exchange of shares, issuance of
rights to subscribe, or change in capital structure), appropriate adjustments
shall be made by any of the Committees or the Board as to the maximum number of
shares subject to the Plan and the number of shares and price per share subject
to outstanding options as shall be equitable to prevent dilution or enlargement
of option rights; provided, however, that any such adjustment shall comply with
the rules of Section 424(a) of the Code and provided further that in no event
shall any adjustment be made that would cause any option granted hereunder to be
considered other than an incentive stock option. Any determination made by any
of the Committees or the Board under this Article VII shall be final, binding
and conclusive upon each Participant.

                                   ARTICLE 8
                                CHANGE IN CONTROL

         Section 8.01. Change In Control. Upon the occurrence of a Change in
Control, each outstanding option under the Plan shall become fully (100%) vested
and exercisable.

For purposes of this Plan, a "CHANGE IN CONTROL" of the Company means the
occurrence of one of the following events:

                  (i) individuals who, on the effective date of the Plan (the
         "EFFECTIVE DATE"), constitute the Board (the "INCUMBENT DIRECTORS")
         cease for any reason to constitute at least a majority of the Board,
         provided that any person becoming a director subsequent to the
         Effective Date whose election or nomination for election was approved
         by a vote of at least two-thirds of the Incumbent Directors then on the
         Board (either by a specific vote or by approval of the proxy statement
         of the Company in which such person is named as a nominee for director,
         without objection to such nomination) shall be an Incumbent Director;
         provided, however, that no individual initially elected or nominated as
         a director of the Company as a result of an actual or threatened
         election contest with respect to directors or as a result of any other
         actual or threatened solicitation of proxies by or on behalf of any
         person other than the Board shall be an Incumbent Director;

                  (ii) any "person" (as such term is defined in Section 3(a)(9)
         of the Securities Exchange Act of 1934 (the "EXCHANGE ACT") and as used
         in Sections 13(d)(3) and 14(d)(2) of the Exchange Act) is or becomes,
         after

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         the Effective Date, a "beneficial owner" (as defined in Rule 13d-3
         under the Exchange Act), directly or indirectly, of securities of the
         Company representing 35% or more of the combined voting power of the
         Company's then outstanding securities eligible to vote for the election
         of the Board (the "COMPANY VOTING SECURITIES"); provided, however, that
         an event described in this paragraph (ii) shall not be deemed to be a
         Change in Control if any of following becomes such a beneficial owner:
         (A) the Company or any majority-owned subsidiary (provided, that this
         exclusion applies solely to the ownership levels of the Company or the
         majority-owned subsidiary), (B) any tax-qualified, broad-based employee
         benefit plan sponsored or maintained by the Company or any
         majority-owned subsidiary, (C) any underwriter temporarily holding
         securities pursuant to an offering of such securities or (D) any person
         pursuant to a Non-Qualifying Transaction (as defined in paragraph
         (iii)).

                  (iii) the consummation of a merger, consolidation, statutory
         share exchange or similar form of corporate transaction involving the
         Company or any of its Subsidiaries that requires the approval of the
         Company's stockholders, whether for such transaction or the issuance of
         securities in the transaction (a "BUSINESS COMBINATION"), unless
         immediately following such Business Combination: (A) 60% or more of the
         total voting power of (x) the corporation resulting from such Business
         Combination (the "SURVIVING CORPORATION"), or (y) if applicable, the
         ultimate parent corporation that directly or indirectly has beneficial
         ownership of 100% of the voting securities eligible to elect directors
         of the Surviving Corporation (the "PARENT CORPORATION"), is represented
         by Company Voting Securities that were outstanding immediately prior to
         such Business Combination (or, if applicable, is represented by shares
         into which such Company Voting Securities were converted pursuant to
         such Business Combination), and such voting power among the holders
         thereof is in substantially the same proportion as the voting power of
         such Company Voting Securities among the holders thereof immediately
         prior to the Business Combination, (B) no person (other than any
         employee benefit plan (or related trust) sponsored or maintained by the
         Surviving Corporation or the Parent Corporation), is or becomes the
         beneficial owner, directly or indirectly, of 35% or more of the total
         voting power of the outstanding voting securities eligible to elect
         directors of the Parent Corporation (or, if there is no Parent
         Corporation, the Surviving Corporation) and (C) at least a majority of
         the members of the board of directors of the Parent Corporation (or if
         there is no Parent Corporation, the Surviving Corporation) following
         the consummation of the Business Combination were Incumbent Directors
         at the time of the Board's approval of the execution of the initial
         agreement providing for such Business Combination (any Business
         Combination which satisfies all of the criteria specified in (A), (B)
         and (C) above shall be deemed to be a "NON-QUALIFYING TRANSACTION"); or

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                  (iv) stockholder approval of a liquidation or dissolution of
         the Company, unless the voting common equity interests of an ongoing
         entity (other than a liquidating trust) are beneficially owned,
         directly or indirectly, by the Company's shareholders in substantially
         the same proportions as such shareholders owned the Company's
         outstanding voting common equity interests immediately prior to such
         liquidation and such ongoing entity assumes all existing obligations of
         the Company under this Plan.

         Notwithstanding the foregoing, a Change in Control of the Company shall
not be deemed to occur solely because any person acquires beneficial ownership
of more than 35% of the Company Voting Securities as a result of the acquisition
of Company Voting Securities by the Company which reduces the number of Company
Voting Securities outstanding; provided, that, if after such acquisition by the
Company such person becomes the beneficial owner of Company Voting Securities
that increases the percentage of outstanding Company Voting Securities
beneficially owned by such person, a Change in Control of the Company shall then
occur.


                                   ARTICLE 9
                            LEGAL REQUIREMENTS, ETC.

         Section 9.01. Revenue Stamps. The Company shall be responsible and
shall pay for any transfer, revenue, or documentary stamps with respect to
shares issued upon the exercise of options granted under the Plan.

         Section 9.02. Legal Requirements. The Company shall not be required to
issue certificates for shares upon the exercise of any option unless and until,
in the opinion of the Company's legal counsel, such issuance would not result in
a violation of any state or Federal securities or other law. Certificates for
shares, when issued, shall have, if required in the opinion of the Company's
legal counsel, the following legend, or statements of other restrictions,
endorsed thereon, and may not be immediately transferable:

                  The shares of Common Stock evidenced by this certificate have
                  been issued to the registered owner in reliance upon written
                  representations that these shares have been purchased for
                  investment. These shares may not be sold, transferred, or
                  assigned unless, in the opinion of the Company and its legal
                  counsel, such sales, transfer, or assignment will not be in
                  violation of the Securities Act of 1933, as amended,
                  applicable rules and regulations of the Securities and
                  Exchange Commission and any applicable state Securities laws.

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         Section 9.03. Private Offering. The options to be granted under the
Plan are available only to a limited number of present and future key executives
and employees of the Company and its subsidiaries who have knowledge of the
Company's financial condition, management, and affairs. Such options are not
intended to provide additional capital for the Company but are to encourage
stock ownership by the Company's key personnel. By the act of accepting an
option, in the absence of an effective registration statement under the
Securities Act of 1933, as amended, Participants shall agree that upon exercise
of such option, they will acquire the shares of Common Stock that are the
subject thereof for investment and not with any intention at such time to resell
or redistribute the same, and they shall confirm such agreement at the time of
exercise, but the neglect or failure to confirm the same in writing shall not be
a limitation of such agreement.


                                   ARTICLE 10
                                     GENERAL

         Section 10.01. Application Of Funds. The proceeds received by the
Company from the sale of shares of Common Stock pursuant to the exercise of
options therefore shall be used for general corporate purposes.

         Section 10.02. Right Of The Company To Terminate Employment. Nothing
contained in the Plan or in a Stock Option Agreement shall confer upon any
Participant any right to be continued in the employ of the Company or of any
subsidiary of the Company, or interfere in any way with the right of the
Company, or such subsidiary, to terminate his employment for any reason
whatsoever, with or without cause, at any time.

         Section 10.03. No Obligation To Exercise. The granting of an option
hereunder shall impose no obligation upon the Participant to exercise such
option.

         Section 10.04. Effectiveness Of Plan. The Plan shall become effective
upon its adoption by the shareholders of the Company. Options may be granted
under the Plan prior to the approval of the Plan by the Shareholders, but no
such option may be exercised prior to such approval.

         Section 10.05. Other Benefits. Participation in the Plan shall not
preclude a Participant from eligibility in any other stock benefit plan of the
Company or any old age benefit, insurance, pension, profit sharing, retirement,
bonus or other plan which the Company has adopted, or may, at any time, adopt
for the benefit of its parents' or its subsidiaries executives and/or employees.

         Section 10.06. Company Records. Records of the Company as to a
Participant's period of employment, termination of employment and the reason
therefore, leaves of absence, re-employment, and other matters will be
conclusive for all purposes hereunder.

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         Section 10.07. Tax Requirement. The exercise or surrender of any
option under this Plan shall constitute a Participant's full and complete
consent to whatever action the Committee elects to satisfy the Federal and state
withholding requirements, if any, which the Committee in its discretion deems
applicable to such exercise.

         Section 10.08. Interpretations And Adjustments. To the extent permitted
by law, an interpretation of the Plan and a decision on any matter within any of
the Committees or Board's discretion made in good faith is binding on all
persons. A misstatement or other mistake of fact shall be corrected when it
becomes known, and the person responsible shall make such adjustment on account
thereof as he considers equitable and practicable.

         Section 10.09. Information. The Company shall, upon request or as may
be specifically required hereunder, furnish or cause to be furnished, all of the
information or documentation which is necessary or required by any of the
Committees or the Board to perform its duties and functions under the Plan.

         Section 10.10. Notice Of Disqualifying Disposition. If a Participant
sells or otherwise disposes of any share of Common Stock transferred to him
pursuant to the exercise of an option granted hereunder within two years from
the date of the granting of the option or within one year of the transfer of
such shares to him (i.e., a "disqualifying disposition"), the Participant,
within ten days thereafter, shall furnish to any of the Committees or the Board
at the principal offices of the Company, written notice of such sale or other
disposition.

         Section 10.11. Governing Law. The Plan and any and all options granted
thereunder shall be governed by, and construed and enforced in accordance with,
the laws of the State of New York from time to time in effect.

         Section 10.12. Certain Definitions.

         (a) "PARENT". The term "parent" shall mean a "parent corporation" as
defined in Section 424(e) of the Code.

         (b) "SUBSIDIARY". The term "subsidiary" shall mean a "subsidiary
corporation" as defined in Section 424(f) of the Code.

         (c) "INCENTIVE STOCK OPTION". The term "incentive stock option" shall
mean an option described in Section 422(b) of the code.

         (d) "DISABLED". The term "disabled" shall have the definition set forth
in Section 22(a)(3) of the Code.


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