Employment Agreement - ImClone Systems Inc. and John Landes


                              EMPLOYMENT AGREEMENT

            AGREEMENT, dated as of September 19, 2001, by and between ImClone
Systems Incorporated, a Delaware corporation (the "Company"), and John Landes
("Executive").

            IN CONSIDERATION of the premises and the mutual covenants set forth
below, the parties hereby agree as follows:

            1.    EMPLOYMENT. The Company hereby agrees to continue to employ
Executive as the General Counsel and Senior Vice President of the Company ("GC")
and Executive hereby accepts such continued employment, on the terms and
conditions hereinafter set forth.

            2.    TERM. The period of employment of Executive by the Company 
under this Agreement (the "Employment Period") shall commence on the date hereof
(the "Commencement Date") and shall continue through the third anniversary
thereof. The Employment Period may be sooner terminated by either party in
accordance with Section 6 of this Agreement.

            3.    POSITION AND DUTIES. During the Employment Period, Executive
shall serve as GC, and shall report solely and directly to the Company's Chief
Executive Officer. Executive shall have those powers and duties normally
associated with the position of GC of entities comparable to the Company and
such other powers and duties as may be prescribed by the Company; PROVIDED THAT,
such other powers and duties are consistent with Executive's position as GC of
the Company. Executive shall devote as much of his working time, attention and
energies during normal business hours (other than absences due to illness or
vacation) to satisfactorily perform his duties for the Company. Notwithstanding
the above, Executive shall be permitted, to the extent such activities do not
substantially interfere with the performance by Executive of his duties and
responsibilities hereunder to (i) manage Executive's personal, financial and
legal affairs and (ii) to serve on civic or charitable boards or committees (it
being expressly understood and agreed that Executive's continuing to serve on
any such board and/or committees on which Executive is serving, or with which
Executive is otherwise associated, as of the Commencement Date shall be deemed
not to interfere with the performance by Executive of his duties and
responsibilities under this Agreement).

            4.    PLACE OF PERFORMANCE. The principal place of employment of
Executive shall be at the Company's principal executive offices in New York, New
York.

            5.    COMPENSATION AND RELATED MATTERS.

                  (a) BASE SALARY AND BONUS. During the Employment Period, the
Company shall pay Executive a base salary at the rate of not less than $225,000
per year ("Base Salary"). Executive's Base Salary shall be paid in approximately
equal installments in accordance with the Company's customary payroll practices.
The Compensation Committee (the "Committee") of the Board of Directors of the
Company (the "Board") shall review Executive's Base Salary for increase (but not
decrease) no less frequently than annually and consistent with 



the compensation practices and guidelines of the Company. If Executive's Base
Salary is increased by the Company, such increased Base Salary shall then
constitute the Base Salary for all purposes of this Agreement. In addition to
Base Salary, Executive shall be paid an annual bonus (the "Bonus") as provided
for under the annual incentive plan maintained by the Company and/or as the
Committee so determines; PROVIDED, THAT, Executive's annual Bonus shall be no
less than $100,000.

                  (b) EXPENSES. The Company shall promptly reimburse Executive
for all reasonable business expenses upon the presentation of reasonably
itemized statements of such expenses in accordance with the Company's policies
and procedures now in force or as such policies and procedures may be modified
with respect to all senior executive officers of the Company.

                  (c) VACATION. Executive shall be entitled to the number of
weeks of paid vacation per year that he was eligible for immediately prior to
the date of this Agreement, or, if greater, the number of weeks provided for by
the Company's vacation policy. In addition to vacation, Executive shall be
entitled to the number of sick days and personal days per year that other senior
executive officers of the Company with similar tenure are entitled under the
Company's policies.

                  (d) SERVICES FURNISHED. During the Employment Period, the
Company shall furnish Executive, with office space, stenographic and secretarial
assistance and such other facilities and services no less favorable than those
that he was receiving immediately prior to the date of this Agreement or, if
better, as provided to other senior executive officers of the Company.

                  (e) WELFARE, PENSION AND INCENTIVE BENEFIT PLANS AND
PERQUISITES. During the Employment Period, Executive (and his spouse and
dependents to the extent provided therein) shall be entitled to participate in
and be covered under all the welfare benefit plans or programs maintained by the
Company from time to time for the benefit of its senior executives including,
without limitation, all medical, hospitalization, dental, disability, accidental
death and dismemberment and travel accident insurance plans and programs. The
Company shall at all times provide to Executive (and his spouse and dependents
to the extent provided under the applicable plans or programs) (subject to
modifications affecting all senior executive officers) the same type and levels
of participation and benefits as are being provided to other senior executives
(and their spouses and dependents to the extent provided under the applicable
plans or programs) on the Commencement Date. In addition, during the Employment
Period, Executive shall be eligible to participate in all pension, retirement,
savings and other employee benefit plans and programs maintained from time to
time by the Company for the benefit of its senior executives. During the
Employment Period, Executive shall be provided such other benefits and
perquisites that are no less favorable than those provided immediately prior to
the Commencement Date.

            6.    TERMINATION. Executive's employment hereunder may be
terminated during the Employment Period under the following circumstances:


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                  (a)   DEATH. Executive's employment hereunder shall terminate
upon his death.

                  (b)   DISABILITY. If, as a result of Executive's incapacity 
due to physical or mental illness, Executive shall have been substantially
unable to perform his duties hereunder for an entire period of six (6)
consecutive months, and within thirty (30) days after written Notice of
Termination is given after such six (6) month period, Executive shall not have
returned to the substantial performance of his duties on a full-time basis, the
Company shall have the right to terminate Executive's employment hereunder for
"Disability", and such termination in and of itself shall not be, nor shall it
be deemed to be, a breach of this Agreement.

                  (c)   CAUSE. The Company shall have the right to terminate
Executive's employment for Cause, and such termination in and of itself shall
not be, nor shall it be deemed to be, a breach of this Agreement. For purposes
of this Agreement, the Company shall have "Cause" to terminate Executive's
employment upon Executive's:

                        (i) final conviction of or plea of guilty or no contest
      to a felony involving moral turpitude; or

                        (ii) willful misconduct that is materially and
      demonstrably injurious economically to the Company.

For purposes of this Section 6(c), no act, or failure to act, by Executive shall
be considered "willful" unless committed in bad faith and without a reasonable
belief that the act or omission was in the best interests of the Company or any
entity in control of, controlled by or under common control with the Company
("Affiliates") thereof. Cause shall not exist under paragraph (ii) unless and
until the Company has delivered to Executive a copy of a resolution duly adopted
by three-quarters of the Board (excluding Executive if he should be serving
thereon) at a meeting of the Board called and held for such purpose (after
reasonable (but in no event less than thirty (30) days) notice to Executive and
an opportunity for Executive, together with his counsel, to be heard before the
Board), finding that in the good faith opinion of the Board, Executive was
guilty of the conduct set forth in paragraph (ii) and specifying the particulars
thereof in detail. This Section 6(c) shall not prevent Executive from
challenging in any arbitration or court of competent jurisdiction the Board's
determination that Cause exists or that Executive has failed to cure any act (or
failure to act) that purportedly formed the basis for the Board's determination.

                  (d)   GOOD REASON. Executive may terminate his employment for
"Good Reason" within ninety (90) days after Executive has actual knowledge of
the occurrence, without the written consent of Executive, of one of the
following events:

                        (i) (A) any change in the duties or responsibilities of
      Executive that is inconsistent in any material and adverse respect with
      Executive's position(s), duties, responsibilities or status with the
      Company (including any material and adverse diminution of such duties or
      responsibilities); PROVIDED, HOWEVER, that Good Reason shall not be deemed
      to occur upon a change in duties or responsibilities that is solely and
      directly a result of the Company no longer being a publicly traded entity
      (other than such change which would have a material and adverse effect on
      Executive's duties or responsibilities) and does not involve any other
      event set forth in this paragraph (d) or 


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      (B) a material and adverse change in Executive's titles or offices
      (including, if applicable, membership on the Board) with the Company;

                        (ii) a reduction in Executive's Base Salary or Bonus
      opportunity;

                        (iii) the relocation of the Company's principal
      executive offices or Executive's own office location outside of Manhattan,
      New York;

                        (iv) the failure of the Company or any Affiliate to
      continue in effect any material employee benefit plan, compensation plan,
      welfare benefit plan or fringe benefit plan in which Executive is
      participating immediately prior to the date of this Agreement or the
      taking of any action by the Company or any Affiliate which would adversely
      affect Executive's participation in or reduce Executive's benefits under
      any such plan, unless Executive is permitted to participate in other plans
      providing Executive with substantially equivalent benefits;

                        (v) any refusal by the Company or any Affiliate to
      continue to permit Executive to engage in activities not directly related
      to the business of the Company which Executive was permitted to engage in
      prior to the date of this Agreement;

                        (vi) any purported termination of Executive's employment
      for Cause which is not effected pursuant to the procedures of Section 6(c)
      (and for purposes of this Agreement, no such purported termination shall
      be effective);

                        (vii) the Company's or any Affiliate's failure to
      provide in all material respects the indemnification set forth in Section
      11 of this Agreement;

                        (viii) the failure of the Company to obtain the
      assumption agreement from any successor as contemplated in Section 13(a);
      or

                        (ix) any other breach of a material provision of this
      Agreement by the Company or any Affiliate.

For purposes of clauses (i) through (vii) and (ix) above, an isolated,
insubstantial and inadvertent action taken in good faith and which is remedied
by the Company within ten (10) days after receipt of notice thereof given by
Executive shall not constitute Good Reason. Executive's right to terminate
employment for Good Reason shall not be affected by Executive's incapacity due
to mental or physical illness and Executive's continued employment shall not
constitute consent to, or a waiver of rights with respect to, any event or
condition constituting Good Reason.

                  (e)   WITHOUT CAUSE. The Company shall have the right to
terminate Executive's employment hereunder without Cause by providing Executive
with a Notice of Termination at least thirty (30) days prior to such
termination, and such termination shall not in and of itself be, nor shall it be
deemed to be, a breach of this Agreement.


                                       4


                  (f)   WITHOUT GOOD REASON. Executive shall have the right to
terminate his employment hereunder without Good Reason by providing the Company
with a Notice of Termination at least thirty (30) days prior to such
termination, and such termination shall not in and of itself be, nor shall it be
deemed to be, a breach of this Agreement.

For purposes of this Agreement, a "Change in Control" of the Company means the
occurrence of one of the following events:

                  (1) individuals who, on the Commencement 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 Commencement 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;

                  (2) 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
      the Commencement 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 (2) 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, (D) any person pursuant to a
      Non-Qualifying Transaction (as defined in paragraph (3)), or (E) Executive
      or any group of persons including Executive (or any entity controlled by
      Executive or any group of persons including Executive);

                  (3) 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 


                                       5


      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

                        (4) 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 to
      Executive under this Agreement.

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.

            7.    TERMINATION PROCEDURE.

                  (a)   NOTICE OF TERMINATION. Any termination of Executive's
employment by the Company or by Executive during the Employment Period (other
than termination pursuant to Section 6(a)) shall be communicated by written
Notice of Termination to the other party hereto in accordance with Section 14.
For purposes of this Agreement, a "Notice of Termination" shall mean a notice
which shall indicate the specific termination provision in this Agreement relied
upon and shall set forth in reasonable detail the facts and circumstances
claimed to provide a basis for termination of Executive's employment under the
provision so indicated.

                  (b)   DATE OF TERMINATION. "Date of Termination" shall mean 
(i) if Executive's employment is terminated by his death, the date of his death,
(ii) if Executive's employment is terminated pursuant to Section 6(b), thirty
(30) days after Notice of Termination (provided that Executive shall not have
returned to the substantial performance of his duties on a 


                                       6


full-time basis during such thirty (30) day period), and (iii) if Executive's
employment is terminated for any other reason, the date on which a Notice of
Termination is given or any later date (within thirty (30) days after the giving
of such notice) set forth in such Notice of Termination.

            8. COMPENSATION UPON TERMINATION OR DURING DISABILITY. In the event
Executive is disabled or his employment terminates during the Employment Period,
the Company shall provide Executive with the payments and benefits set forth
below. Executive acknowledges and agrees that the payments set forth in this
Section 8 constitute liquidated damages for termination of his employment during
the Employment Period.

                  (a) TERMINATION BY COMPANY WITHOUT CAUSE OR BY EXECUTIVE FOR
GOOD REASON. If Executive's employment is terminated by the Company without
Cause or by Executive for Good Reason:

                        (i) within five (5) days following such termination, the
      Company shall pay to Executive (A) his Base Salary and Bonus earned and/or
      accrued, but unpaid through the Date of Termination, as soon as
      practicable following the Date of Termination, (B) a pro rata portion of
      Executive's annual bonus for the fiscal year in which Executive's Date of
      Termination occurs in an amount at least equal to (1) Executive's target
      Bonus amount, multiplied by (2) a fraction, the numerator of which is the
      number of days in the fiscal year in which the Date of Termination occurs
      through the Date of Termination and the denominator of which is three
      hundred sixty-five (365) (the "Pro-Rated Bonus"); (C) any accrued vacation
      pay; and (D) a lump-sum cash payment equal to three (3) times the sum of
      Executive's Base Salary and highest Bonus paid to Executive in the
      three-year period immediately preceding such termination (including, for
      this purpose, any and all bonuses paid to Executive prior to the date of
      this Agreement); PROVIDED, THAT, for purposes of this Section 8(a)(i), 
      Executive's Bonus shall be deemed to be no less than $100,000; and

                        (ii) the Company shall maintain in full force and
      effect, for the continued benefit of Executive, his spouse and his
      dependents for a period of three (3) years following the Date of
      Termination the medical, hospitalization, dental, and life insurance
      programs in which Executive, his spouse and his dependents were
      participating immediately prior to the Date of Termination at the level in
      effect and upon substantially the same terms and conditions (including
      without limitation contributions required by Executive for such benefits)
      as existed immediately prior to the Date of Termination; PROVIDED, THAT,
      if Executive, his spouse or his dependents cannot continue to participate
      in the Company programs providing such benefits, the Company shall arrange
      to provide Executive, his spouse and his dependents with the economic
      equivalent of such benefits which they otherwise would have been entitled
      to receive under such plans and programs ("Continued Benefits"), PROVIDED,
      THAT, such Continued Benefits shall terminate on the date or dates
      Executive receives equivalent coverage and benefits, without waiting
      period or pre-existing condition limitations, under the plans and programs
      of a subsequent employer (such coverage and benefits to be determined on a
      coverage-by-coverage or benefit-by-benefit, basis); and


                                       7


                        (iii) the Company shall reimburse Executive pursuant to
      Section 5 for reasonable expenses incurred, but not paid prior to such
      termination of employment; and

                        (iv) Executive shall be entitled to any other rights,
      compensation and/or benefits as may be due to Executive in accordance with
      the terms and provisions of any agreements, plans or programs of the
      Company; and

                        (v) with respect to equity awards granted or made on or
      after the Commencement Date, notwithstanding the terms or conditions of
      any stock option, stock appreciation right, restricted stock or similar
      agreements between the Company and Executive to the contrary, and for
      purposes thereof, such agreements shall be deemed to be amended in
      accordance with this Section 8(a)(v) if need be as of the Date of
      Termination and neither the Company, the Board nor the Committee shall
      take or assert any position contrary to the foregoing, such that Executive
      shall vest, as of the Date of Termination, in all rights under such
      agreements (E.G., stock options that would otherwise vest after the
      Date of Termination) and in the case of stock options, stock appreciation
      rights or similar awards, thereafter shall be permitted to exercise any
      and all such rights until the end of the term of such awards (regardless
      of any termination of employment restrictions therein contained) and
      restricted stock held by Executive shall become immediately vested as of
      the Date of Termination; and

                        (vi) Executive shall be paid a lump sum payment equal to
      the present value of the Company contributions that would have been made
      under all Company savings programs (whether or not intended to be
      qualified under Section 401(a) of the Internal Revenue Code of 1986, as
      amended (the "Code") if Executive had continued in the employ of the
      Company for an additional three (3) years following his Date of
      Termination earning during such three-year period the rate of Base Salary
      and Bonus in effect as of his Date of Termination, assuming that the
      Company would have made the maximum contributions permitted under such
      savings programs, and assuming, for purposes of determining the amount of
      any Company matching contributions, that Executive would have contributed
      the amount necessary to receive the maximum matching contributions
      available under such savings programs; and

                        (vii) Any and all insurance benefits or policies for the
      benefit of Executive shall become the sole property of Executive and, to
      the extent applicable, all of the Company's rights therein (including
      repayment of premiums) shall be forfeited by the Company and, to the
      extent not already made, the Company shall make all contributions or
      payments required of such policies for the year of termination.

                  (b) CAUSE OR BY EXECUTIVE WITHOUT GOOD REASON. If Executive's
employment is terminated by the Company for Cause or by Executive (other than
for Good Reason):

                        (i) the Company shall pay Executive his Base Salary,
      Bonus and his accrued vacation pay through the Date of Termination, as
      soon as practicable following the Date of Termination; and


                                       8


                        (ii) the Company shall reimburse Executive pursuant to
      Section 5 for reasonable expenses incurred, but not paid prior to such
      termination of employment; and

                        (iii) Executive shall be entitled to any other rights,
      compensation and/or benefits as may be due to Executive in accordance with
      the terms and provisions of any agreements, plans or programs of the
      Company.

                  (c)   DISABILITY. During any period that Executive fails to
perform his duties hereunder as a result of incapacity due to physical or mental
illness ("Disability Period"), Executive shall continue to receive his full Base
Salary set forth in Section 5(a) until his employment is terminated pursuant to
Section 6(b). In the event Executive's employment is terminated for Disability
pursuant to Section 6(b):

                        (i) the Company shall pay to Executive (A) his Base
      Salary, Bonus and accrued vacation pay through the Date of Termination, as
      soon as practicable following the Date of Termination, (B) his Pro-Rated
      Bonus and (C) Continued Benefits for one (1) year; and

                        (ii) the Company shall reimburse Executive pursuant to
      Section 5 for reasonable expenses incurred, but not paid prior to such
      termination of employment; and

                        (iii) Executive shall be entitled to any other rights,
      compensation and/or benefits as may be due to Executive in accordance with
      the terms and provisions of any agreements, plans or programs of the
      Company.

            (d)   DEATH. If Executive's employment is terminated by his death:

                        (i) the Company shall pay in a lump sum to Executive's
      beneficiary, legal representatives or estate, as the case may be,
      Executive's Base Salary, Bonus and accrued vacation pay through the Date
      of Termination, his Pro-Rated Bonus and shall provide Executive's spouse
      and dependents with Continued Benefits for two (2) years; and

                        (ii) the Company shall reimburse Executive's
      beneficiary, legal representatives, or estate, as the case may be,
      pursuant to Section 5 for reasonable expenses incurred, but not paid prior
      to such termination of employment; and

                        (iii) Executive's beneficiary, legal representatives or
      estate, as the case may be, shall be entitled to any other rights,
      compensation and benefits as may be due to any such persons or estate in
      accordance with the terms and provisions of any agreements, plans or
      programs of the Company.

            (e)   ADDITIONAL PAYMENTS. (i) Anything in this Agreement to the
contrary notwithstanding, in the event it shall be determined that any payment,
award, benefit or distribution (or any acceleration of any payment, award,
benefit or distribution) by the Company or any entity which effectuates a Change
in Control (or other change in ownership) to or for the 


                                       9


benefit of Executive (the "Payments") would be subject to the excise tax imposed
by Section 4999 of the Code, or any interest or penalties are incurred by
Executive with respect to such excise tax (such excise tax, together with any
such interest and penalties, are hereinafter collectively referred to as the
"Excise Tax"), then the Company shall pay to Executive an additional payment (a
"Gross-Up Payment") in an amount such that after payment by Executive of all
taxes (including any Excise Tax) imposed upon the Gross-Up Payment, Executive
retains an amount of the Gross-Up Payment equal to the sum of (x) the Excise Tax
imposed upon the Payments and (y) the product of any deductions disallowed
because of the inclusion of the Gross-Up Payment in Executive's adjusted gross
income and the highest applicable marginal rate of federal income taxation for
the calendar year in which the Gross-Up Payment is to be made. For purposes of
determining the amount of the Gross-Up Payment, Executive shall be deemed to (A)
pay federal income taxes at the highest marginal rates of federal income taxes
at the highest marginal rate of taxation for the calendar year in which the
Gross-Up Payment is to be made, (B) pay applicable state and local income taxes
at the highest marginal rate of taxation for the calendar year in which the
Gross-Up Payment is to be made, net of the maximum reduction in federal income
taxes which could be obtained from deduction of such state and local taxes and
(C) have otherwise allowable deductions for federal income tax purposes at least
equal to those which could be disallowed because of the inclusion of the
Gross-Up Payment in Executive's adjusted gross income. Notwithstanding the
foregoing provisions of this Section 8(e)(i), if it shall be determined that
Executive is entitled to a Gross-Up Payment, but that the Payments would not be
subject to the Excise Tax if the Payments were reduced by an amount that is less
than 10% of the portion of the Payments that would be treated as "parachute
payments" under Section 280G of the Code, then the amounts payable to Executive
under this Agreement shall be reduced (but not below zero) to the maximum amount
that could be paid to Executive without giving rise to the Excise Tax (the "Safe
Harbor Cap"), and no Gross-Up Payment shall be made to Executive. The reduction
of the amounts payable hereunder, if applicable, shall be made by reducing first
the payments under Section 8(a)(i)(D), unless an alternative method of reduction
is elected by Executive. For purposes of reducing the Payments to the Safe
Harbor Cap, only amounts payable under this Agreement (and no other Payments)
shall be reduced. If the reduction of the amounts payable hereunder would not
result in a reduction of the Payments to the Safe Harbor Cap, no amounts payable
under this Agreement shall be reduced pursuant to this provision.

            (ii) Subject to the provisions of Section 8(e)(i), all
determinations required to be made under this Section 8(e), including whether
and when a Gross-Up Payment is required, the amount of such Gross-Up Payment,
the reduction of the Payments to the Safe Harbor Cap and the assumptions to be
utilized in arriving at such determinations, shall be made by a nationally
recognized public accounting firm that is retained by the Company (the
"Accounting Firm"). In the event that the Accounting Firm is serving as
accountant or auditor for the individual, entity or group effecting the Change
in Control (or change in ownership), Executive may appoint another nationally
recognized public accounting firm to make the determinations required hereunder
(which accounting firm shall then be referred to as the Accounting Firm
hereunder). The Accounting Firm shall provide detailed supporting calculations
both to the Company and Executive within fifteen (15) business days of the
receipt of notice from the Company or the Executive that there has been a
Payment, or such earlier time as is requested by the Company (collectively, the
"Determination"). All fees and expenses of the Accounting Firm shall be borne
solely by the Company and the Company shall enter into any agreement requested


                                       10


by the Accounting Firm in connection with the performance of the services
hereunder. The Gross-up Payment under this Section 8(e) with respect to any
Payments shall be made no later than thirty (30) days following such Payment. If
the Accounting Firm determines that no Excise Tax is payable by Executive, it
shall furnish Executive with a written opinion to such effect, and to the effect
that failure to report the Excise Tax, if any, on Executive's applicable federal
income tax return should not result in the imposition of a negligence or similar
penalty. In the event the Accounting Firm determines that the Payments shall be
reduced to the Safe Harbor Cap, it shall furnish Executive with a written
opinion to such effect. The Determination by the Accounting Firm shall be
binding upon the Company and Executive.

            (iii) As a result of the uncertainty in the application of Section
4999 of the Code at the time of the Determination, it is possible that Gross-Up
Payments which will not have been made by the Company should have been made
("Underpayment") or Gross-Up Payments are made by the Company which should not
have been made ("Overpayment"), consistent with the calculations required to be
made hereunder. In the event that the Executive thereafter is required to make
payment of any Excise Tax or additional Excise Tax, the Accounting Firm shall
determine the amount of the Underpayment that has occurred and any such
Underpayment (together with interest at the rate provided in Section
1274(b)(2)(B) of the Code) shall be promptly paid by the Company to or for the
benefit of Executive. In the event the amount of the Gross-up Payment exceeds
the amount necessary to reimburse the Executive for his Excise Tax, the
Accounting Firm shall determine the amount of the Overpayment that has been made
and any such Overpayment (together with interest at the rate provided in Section
1274(b)(2) of the Code) shall be promptly paid by Executive to or for the
benefit of the Company. Executive shall cooperate, to the extent his expenses
are reimbursed by the Company, with any reasonable requests by the Company in
connection with any contests or disputes with the Internal Revenue Service in
connection with the Excise Tax.

            9.    MITIGATION. Executive shall not be required to mitigate 
amounts payable under this Agreement by seeking other employment or otherwise,
and there shall be no offset against amounts due Executive under this Agreement
on account of subsequent employment except as specifically provided herein.
Additionally, amounts owed to Executive under this Agreement shall not be offset
by any claims the Company may have against Executive and the Company's
obligation to make the payments provided for in this Agreement and otherwise to
perform its obligations hereunder, shall not be affected by any other
circumstances, including, without limitation, any counterclaim, recoupment,
defense or other right which the Company may have against Executive or others.

            10.   RESTRICTIVE COVENANTS.

                  (a) CONFIDENTIAL INFORMATION. Executive shall hold in a
fiduciary capacity for the benefit of the Company all trade secrets and
confidential information, knowledge or data relating to the Company and its
businesses and investments, which shall have been obtained by Executive during
Executive's employment by the Company and which is not generally available
public knowledge (other than by acts by Executive in violation of this
Agreement). Except as may be required or appropriate in connection with his
carrying out his duties under this Agreement, Executive shall not, without the
prior written consent of the Company or as may otherwise be required by law or
any legal process, or as is necessary in 


                                       11


connection with any adversarial proceeding against the Company (in which case
Executive shall use his reasonable best efforts in cooperating with the Company
in obtaining a protective order against disclosure by a court of competent
jurisdiction), communicate or divulge any such trade secrets, information,
knowledge or data to anyone other than the Company and those designated by the
Company or on behalf of the Company in the furtherance of its business or to
perform duties hereunder.

            (b) NON-SOLICITATION. Executive hereby agrees, in consideration of
his employment hereunder and in view of the confidential position to be held by
Executive hereunder, that after his termination of employment in which he is
entitled to the benefits set forth in Section 8(a) hereof and through the first
anniversary thereof, Executive shall not directly or indirectly induce any
employee of the Company to terminate such employment or to become employed by
any other biopharmaceutical company.

            (c) NON-COMPETITION. Executive hereby agrees, in consideration of
his employment hereunder and in view of the confidential position to be held by
Executive hereunder, that after his termination of employment in which he is
entitled to the benefits set forth in Section 8(a) hereof and through the first
anniversary thereof, he shall not be employed by or perform activities on behalf
of, or have an ownership interest in, any person, firm, corporation or other
entity, or in connection with any business enterprise, that is directly or
indirectly engaged in any of the biopharmaceutical business in which the Company
and its subsidiaries have significant involvement (other than direct or
beneficial ownership of up to one percent (1%) of any entity whether or not in
the same or competing business).

            (d) BLUE PENCIL. The parties hereby acknowledge that the
restrictions in this Section 10 have been specifically negotiated and agreed to
by the parties hereto and are limited only to those restrictions necessary to
protect the Company and its subsidiaries from unfair competition. The parties
hereby agree that if the scope or enforceability of any provision, paragraph or
subparagraph of this Section 10 is in any way disputed at any time, and should a
court find that such restrictions are overly broad, the court may modify and
enforce the covenant to the extent that it believes to be reasonable under the
circumstances. Each provision, paragraph and subparagraph of this Section 10 is
separable from every other provision, paragraph, and subparagraph and
constitutes a separate and distinct covenant. Executive acknowledges that the
Company's business is not limited by geographical scope, is operating throughout
the world and that the effect of Section 10(c) may be to prevent him from
working in a competitive business after his termination of employment hereunder.

            (e) REMEDIES. Executive hereby expressly acknowledges that any
breach or threatened breach by Executive of any of the terms set forth in
Section 10 of this Agreement may result in significant and continuing injury to
the Company, the monetary value of which would be impossible to establish.
Therefore, Executive agrees that the Company shall be entitled to apply for
injunctive relief in a court of appropriate jurisdiction.

            11. INDEMNIFICATION. The Company agrees that if Executive is made a
party or a threatened to be made a party to any action, suit or proceeding,
whether civil, criminal, administrative or investigative (a "Proceeding"), by
reason of the fact that Executive is or was a trustee, director or officer of
the Company or any subsidiary of the Company or is or was serving 


                                       12


at the request of the Company or any subsidiary as a trustee, director, officer,
member, employee or agent of another corporation or a partnership, joint
venture, trust or other enterprise, including, without limitation, service with
respect to employee benefit plans, whether or not the basis of such Proceeding
is alleged action in an official capacity as a trustee, director, officer,
member, employee or agent while serving as a trustee, director, officer, member,
employee or agent, Executive shall be indemnified and held harmless by the
Company to the fullest extent authorized by Delaware law, as the same exists or
may hereafter be amended, against all Expenses incurred or suffered by Executive
in connection therewith, and such indemnification shall continue as to Executive
even if Executive has ceased to be an officer, director, trustee or agent, or is
no longer employed by the Company and shall inure to the benefit of his heirs,
executors and administrators. As used in this Agreement, the term "Expenses"
shall include, without limitation, damages, losses, judgments, liabilities,
fines, penalties, excise taxes, settlements, and costs, attorneys' fees,
accountants' fees, and disbursements and costs of attachment or similar bonds,
investigations, and any expenses of establishing a right to indemnification
under this Agreement.

            12.   LEGAL FEES; ARBITRATION. As soon as administratively possible
following the Commencement Date and in any case, within 10 business days
thereafter, the Company shall reimburse Executive for his legal fees and
expenses associated with the preparation and negotiation of this Agreement.
Except as provided for in Section 10 of this Agreement, if any contest or
dispute arises between the parties with respect to this Agreement, such contest
or dispute shall be submitted to binding arbitration for resolution in New York,
New York in accordance with the rules and procedures of the Employment Dispute
Resolution Rules of the American Arbitration Association then in effect. The
decision of the arbitrator shall be final and binding on both parties, and any
court of competent jurisdiction may enter judgment upon the award. The Company
shall pay all expenses relating to such arbitration, including, but not limited
to, Executive's legal fees and expenses, regardless of outcome, unless the
arbitrator determines that Executive has acted in bad faith.

            13.   SUCCESSORS; BINDING AGREEMENT.

                  (a) COMPANY'S SUCCESSORS. No rights or obligations of the
Company under this Agreement may be assigned or transferred except that the
Company will require any successor (whether direct or indirect, by purchase,
merger, consolidation or otherwise) to all or substantially all of the business
and/or assets of the Company to expressly assume and agree to perform this
Agreement in the same manner and to the same extent that the Company would be
required to perform it if no such succession had taken place. As used in this
Agreement, "Company" shall mean the Company as herein before defined and any
successor to its business and/or assets (by merger, purchase or otherwise) which
executes and delivers the agreement provided for in this Section 13 or which
otherwise becomes bound by all the terms and provisions of this Agreement by
operation of law.

                  (b) EXECUTIVE'S SUCCESSORS. No rights or obligations of
Executive under this Agreement may be assigned or transferred by Executive other
than his rights to payments or benefits hereunder, which may be transferred only
by will or the laws of descent and distribution. Upon Executive's death, this
Agreement and all rights of Executive hereunder shall inure to the benefit of
and be enforceable by Executive's beneficiary or beneficiaries, 


                                       13


personal or legal representatives, or estate, to the extent any such person
succeeds to Executive's interests under this Agreement. Executive shall be
entitled to select and change a beneficiary or beneficiaries to receive any
benefit or compensation payable hereunder following Executive's death by giving
the Company written notice thereof. In the event of Executive's death or a
judicial determination of his incompetence, reference in this Agreement to
Executive shall be deemed, where appropriate, to refer to his beneficiary(ies),
estate or other legal representative(s). If Executive should die following his
Date of Termination while any amounts would still be payable to him hereunder if
he had continued to live, all such amounts unless otherwise provided herein
shall be paid in accordance with the terms of this Agreement to such person or
persons so appointed in writing by Executive, or otherwise to his legal
representatives or estate.

            14. NOTICE. For the purposes of this Agreement, notices, demands and
all other communications provided for in this Agreement shall be in writing and
shall be deemed to have been duly given when delivered either personally or by
United States certified or registered mail, return receipt requested, postage
prepaid, addressed as follows:

            If to Executive:

            c/o ImClone Systems Incorporated
            180 Varick Street
            New York, New York  10014


            If to the Company:

            ImClone Systems Incorporated
            180 Varick Street
            New York, New York  10014
            Attention:  Chief Operating Officer

or to such other address as any party may have furnished to the others in
writing in accordance herewith, except that notices of change of address shall
be effective only upon receipt.

            15. MISCELLANEOUS. No provisions of this Agreement may be amended,
modified, or waived unless such amendment or modification is agreed to in
writing signed by Executive and by a duly authorized officer of the Company, and
such waiver is set forth in writing and signed by the party to be charged. No
waiver by either party hereto at any time of any breach by the other party
hereto of any condition or provision of this Agreement to be performed by such
other party shall be deemed a waiver of similar or dissimilar provisions or
conditions at the same or at any prior or subsequent time. No agreements or
representations, oral or otherwise, express or implied, with respect to the
subject matter hereof have been made by either party which are not set forth
expressly in this Agreement. The respective rights and obligations of the
parties hereunder of this Agreement shall survive Executive's termination of
employment and the termination of this Agreement to the extent necessary for the
intended preservation of such rights and obligations. The validity,
interpretation, construction and 


                                       14


performance of this Agreement shall be governed by the laws of the State of New
York without regard to its conflicts of law principles.

            16. VALIDITY. The invalidity or unenforceability of any provision or
provisions of this Agreement shall not affect the validity or enforceability of
any other provision of this Agreement, which shall remain in full force and
effect.

            17. COUNTERPARTS. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original but all of which
together will constitute one and the same instrument.

            18. ENTIRE AGREEMENT. Except as other provided herein, this
Agreement sets forth the entire agreement of the parties hereto in respect of
the subject matter contained herein and supersede all prior agreements,
promises, covenants, arrangements, communications, representations or
warranties, whether oral or written, by any officer, employee or representative
of any party hereto in respect of such subject matter. Except as other provided
herein, any prior agreement of the parties hereto in respect of the subject
matter contained herein is hereby terminated and cancelled.

            19. WITHHOLDING. All payments hereunder shall be subject to any
required withholding of Federal, state and local taxes pursuant to any
applicable law or regulation.

            20. NONCONTRAVENTION. The Company represents that the Company is not
prevented from entering into, or performing this Agreement by the terms of any
law, order, rule or regulation, its by-laws or declaration of trust, or any
agreement to which it is a party, other than which would not have a material
adverse effect on the Company's ability to enter into or perform this Agreement.

            21. SECTION HEADINGS. The section headings in this Agreement are for
convenience of reference only, and they form no part of this Agreement and shall
not affect its interpretation.




                                       15




            IN WITNESS WHEREOF, the parties hereto have executed this Agreement
on the date first above written.

                                    IMCLONE SYSTEMS INCORPORATED



                                    By:  /s/ Samuel D. Waksal
                                        ----------------------------------
                                        Name:  Samuel D. Waksal
                                        Title: President & Chief Executive
                                               Officer


                                     /s/ John B. Landes, Esq.
                                    --------------------------------------
                                    John B. Landes, Esq.





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