Exhibit 99(a)(M)


                      MEMORANDUM TO ELIGIBLE OPTION HOLDERS


TO:    Holders of Stock Options Described Below
DATE:  September 28, 2001
RE:    Tender of Option Shares in Tender Offer Referred to Below


      The following questions and answers have been prepared for your
convenience. Please review this information together with the Offer to Purchase
and other documents you received along with this memorandum. If, after reviewing
the information provided, you have additional questions, please call either the
Company's Finance Department in New Jersey or the Company's Legal Department in
New York. You may also call Catherine Vaczy, Vice President, Legal and Associate
General Counsel of the Company, at (646) 638-5032 or Kurt Elster, Controller of
the Company, at (908) 541-8111.

      1. WHAT IS THE OFFER?


      Bristol-Myers Squibb Biologics Company, a Delaware corporation
("Purchaser") and a wholly owned subsidiary of Bristol-Myers Squibb Company, a
Delaware corporation ("Parent"), is offering to purchase up to 14,392,003 shares
of common stock, par value $0.001 per share (the "Shares"), of ImClone Systems
Incorporated (the "Company") at a price of $70.00 per Share (the "Offer"). The
Offer will be open until it expires at 12:00 midnight, New York City time, on
October 26, 2001 (the "Expiration Date"), unless it is otherwise extended by
Purchaser.

      In connection with this Offer, present and former employees and directors
of the Company holding exercisable options to purchase Shares having exercise
prices of less than $70.00 per Share may conditionally exercise all or part of
such options and tender Shares issuable upon such conditional exercise (the
"Option Shares") in the Offer. The portion of your options with respect to any
Option Shares not accepted for payment and paid for by Purchaser (due to
proration or otherwise) will not be considered to have been exercised and will
continue to be outstanding options.

      You must complete and deliver to the Company the Notice of Conditional
Exercise in order to tender any or all of your Option Shares resulting from a
conditional exercise of eligible options. This exercise of your options is
"conditional" because you will be deemed to exercise the option only if, and to
the



extent, that Purchaser actually accepts for payment and pays for the Option
Shares in the Offer.

      The Offer, which is subject to a number of other conditions, is described
in the Offer to Purchase dated September 28, 2001, and related Letter of
Transmittal included in this package. Please read these documents carefully,
together with the following materials:

      o     Instructions for Conditional Exercise.

      o     Notice of Conditional Exercise.

      NEITHER THE COMPANY NOR THE BOARD OF DIRECTORS OF THE COMPANY MAKES ANY
RECOMMENDATION AS TO WHETHER HOLDERS OF SUCH OPTIONS SHOULD EXERCISE OR REFRAIN
FROM EXERCISING (CONDITIONALLY OR OTHERWISE) SUCH OPTIONS IN ORDER TO TENDER
SHARES (INCLUDING OPTION SHARES) IN THE OFFER, SINCE THAT DECISION REQUIRES AN
ANALYSIS OF EACH INDIVIDUAL OPTION HOLDER'S SPECIFIC CIRCUMSTANCES. EACH HOLDER
OF SUCH OPTIONS IS URGED TO CONSULT HIS OR HER OWN TAX, FINANCIAL AND LEGAL
ADVISORS REGARDING THE U.S. FEDERAL, STATE, LOCAL AND FOREIGN TAX CONSEQUENCES
OF CONDITIONALLY EXERCISING HIS OR HER OPTIONS IN LIGHT OF HIS OR HER OWN
PARTICULAR CIRCUMSTANCES. EACH HOLDER OF SUCH OPTIONS IS URGED TO CONSIDER (IN
CONJUNCTION WITH HIS OR HER TAX, FINANCIAL AND LEGAL ADVISORS) THE FINANCIAL
IMPLICATIONS OF EXERCISING OPTIONS SIGNIFICANTLY IN ADVANCE OF THE EXPIRATION OF
THE OPTION TERM.

      You must carefully follow the instructions below and in the enclosed
Instructions for Conditional Exercise and Notice of Conditional Exercise if you
want to conditionally exercise options and tender Option Shares in the Offer.
Failure to follow such instructions may invalidate your attempted tender of
Option Shares in the Offer.

      2.    MUST I ACTUALLY EXERCISE MY OPTIONS IN ORDER TO PARTICIPATE IN THE
            OFFER?

      No. As a holder of exercisable options you may "conditionally" exercise
all or part of your exercisable options having exercise prices of less than
$70.00 per share and tender the Option Shares you would be entitled to receive
upon such exercise.

      This exercise of options is "conditional" because you are deemed to
exercise the option only if, and to the extent that, Purchaser actually accepts
for payment and pays for the underlying Option Shares in the Offer.


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      3.    DO I HAVE TO PAY THE EXERCISE PRICE OR WITHHOLDING TAXES WITH CASH?

      No. In order to facilitate your participation in the Offer, the Company is
allowing you to conditionally exercise your options without paying the exercise
price in cash at the time of exercise. This is called a "cashless exercise".
This means that your options will be conditionally exercised and the Option
Shares will be tendered, and the amount of cash you receive for each Option
Share purchased pursuant to the Offer will equal the difference between $70.00
and the option exercise price per Share, less withholding taxes. You do not need
to send any money with your Notice of Conditional Exercise.

      4.    WILL ALL OF THE OPTION SHARES THAT I TENDER BE PURCHASED IN THE
            OFFER?

      In the Offer, Purchaser is offering to purchase up to 14,392,003 Shares
(including Option Shares). If more than this number of Shares is tendered,
Purchaser will purchase Shares on a pro rata basis. This means that Purchaser
will not purchase all of the Option Shares you tender under these circumstances.
The number of Shares that will be tendered in the Offer cannot be determined at
this time. If, after taking into account proration, Purchaser purchases only a
portion of your Option Shares, your remaining options relating to Option Shares
will not be considered to have been exercised and will continue to be
outstanding. If less than 14,392,003 Shares (including Option Shares) are
tendered in the Offer, Purchaser will purchase all of the Option Shares you
tender.

      EXAMPLE: If you conditionally exercise options to purchase 2,000 Shares in
the Offer, and at the expiration of the Offer a total of 28,784,006 Shares
(including Option Shares) have been validly tendered and not withdrawn and all
of the conditions to the Offer have been satisfied or waived, Purchaser will
purchase only 14,392,003 Shares. Of your 2,000 Option Shares tendered, 1,000
Option Shares will be purchased by Purchaser. The remaining options to purchase
1,000 Shares will not be considered to have been exercised and will continue to
be outstanding options.

      5.    HOW WILL I KNOW IF MY OPTION SHARES HAVE BEEN PURCHASED AND WHEN
            WILL I BE PAID?

      After the Offer expires, all validly tendered Shares (including validly
tendered Option Shares) will be tabulated. Purchaser anticipates that this will
take approximately four trading days after the expiration of the Offer. You can
receive preliminary information regarding the number of your Option Shares that
were purchased in the Offer by contacting the Information Agent at the numbers
set forth on the back cover of the Offer to Purchase. Once the proration factor
is


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determined, options will be exercised to the extent that the related Option
Shares are purchased in the Offer; these Option Shares will be delivered to the
Depositary. The Depositary will send funds to the Company for disbursement to
holders of Option Shares that were purchased in the Offer. The Company will
disburse to you the purchase price of all of your Option Shares purchased in the
Offer, less the applicable exercise price or prices and applicable withholding
taxes, promptly thereafter.

      6.    DO I HAVE TO CONDITIONALLY EXERCISE ALL OR PART OF MY OPTIONS?

      No. You may elect to conditionally exercise in full, in part or not at
all. If you conditionally exercise in full or in part, the number of options
ultimately exercised and the number of Option Shares purchased in the Offer will
depend on the proration factor, as described above.

      7.    WILL I BE TAXED ON THE MONEY I RECEIVE?

      You should read Section 5, "Certain U.S. Federal Income Tax Consequences",
of the Offer to Purchase for information regarding the tax consequences of your
receipt of money in exchange for your Option Shares.

      8.    WHAT WILL HAPPEN TO ANY OPTIONS I STILL HOLD AFTER THE OFFER?

      If, after taking into account proration, Purchaser does not purchase all
of your Option Shares, the remaining options will not be considered to have been
exercised and will continue to be outstanding options.

      9.    HOW DO I TENDER MY OPTION SHARES IN THE OFFER?

      The only way that you can conditionally exercise options and tender Option
Shares in the Offer is by completing the Notice of Conditional Exercise, signing
the form, and returning it to the Company. The Notice of Conditional Exercise
must be received by the Company before 5:00 P.M., New York City time, on
Wednesday, October 24, 2001.

         On this form, you will conditionally exercise part or all of your
eligible options and tender your Option Shares in the Offer.

      10.   WHAT IF I HOLD ACTUAL SHARES OF THE COMPANY IN ADDITION TO MY STOCK
            OPTIONS?

      If you have actual Shares in your possession (or at a brokerage firm), you
may tender those Shares as well. In this case, you may have received two or more


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sets of Offer materials. You should be careful to follow the separate directions
that apply to Shares and Option Shares.

      11.   CAN I CHANGE MY MIND AND WITHDRAW OPTION SHARES THAT I DIRECTED TO
            BE TENDERED?

      Yes, but only if you perform the following steps:

      o     You must send a signed notice of withdrawal to the Company, and it
            must be received by the Company before 5:00 PM, New York City time,
            on October 24, 2001.

      o     The notice of withdrawal must be in writing. You may fax your notice
            of withdrawal to the Company's Finance Department, Attn: Conditional
            Exercise Team, at (908) 704-8256.

      The withdrawal procedures are described in the Instructions for
Conditional Exercise. You must follow these instructions carefully.

      You are entitled to conditionally exercise eligible options and retender
Option Shares after withdrawal, provided that all resubmitted materials are
completed properly and delivered on time in accordance with the instructions
applicable to the original submission.

      12.   WHAT DO I DO IF I HAVE ANY QUESTIONS ABOUT THE TENDER OFFER?

      If you have questions about the Offer or need help in properly responding
to the Offer, you may call either the Company's Finance Department in New Jersey
or the Company's Legal Department in New York. You may also call Catherine
Vaczy, Vice President, Legal and Associate General Counsel of the Company, at
(646) 638-5032 or Kurt Elster, Controller of the Company, at (908) 541-8111.


                                     ******

      This memorandum is intended to help you understand the Offer and how
options will be handled in the Offer. The Offer to Purchase and Letter of
Transmittal contain the legal terms of the Offer, and are controlling. We urge
you to carefully read these documents, which explain the Offer in detail.


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