PROSPECTUS SUPPLEMENT                           FILED PURSUANT TO RULE 424(B)(3)
TO PROSPECTUS DATED JULY 31, 2000                     REGISTRATION NO. 333-37746


                                  $240,000,000

                          IMCLONE SYSTEMS INCORPORATED

                 5 1/2% Convertible Subordinated Notes Due 2005

     This prospectus supplement relates to the resale by the holders of our 5
1/2% Convertible Subordinated Notes Due 2005 and the shares of our common stock
issuable upon the conversion of the notes.

     This prospectus supplement should be read in conjunction with the
prospectus dated July 31, 2000, which is to be delivered with this prospectus
supplement. All capitalized terms used but not defined in the prospectus
supplement shall have the meanings given to them in the prospectus.

     The table below sets forth information as of the date hereof concerning
beneficial ownership of the securities of the selling holders as listed below.
All information concerning beneficial ownership has been furnished by the
selling holders.


                                PRINCIPAL AMOUNT OF  COMMON STOCK
- -------------------------------  NOTES BENEFICIALLY   OWNED PRIOR  COMMON STOCK
                                 OWNED AND OFFERED      TO THE        OFFERED
                                      HEREBY
                                -------------------  ------------  -------------

Allstate Insurance Company.....       2,100,000          19,059       19,059
CIBC World Markets.............      17,194,000         156,053      156,053
J.P. Morgan Securities, Inc....       3,255,000          29,542       29,542
McMahon Securities Co. L.P.....       1,000,000           9,076        9,076
- -------------------

(1)  Assumes a conversion price of $110.18 per share and a cash payment in lieu
     of any fractional interest.

(2)  Assumes that any holders of notes or any future transferee from any such
     holder does not beneficially own any common stock other than common stock
     into which the notes are convertible at the conversion price of $110.18
     per share.

Other than as may be stated in any additional prospectus supplement, none of
the selling holders has had any material relationship with us or with our
affiliates within the past three years.

                            -----------------------

     The securities offered hereby involve a high degree of risk. See "Risk
                Factors" beginning on page 4 of the prospectus.

  These securities have not been approved or disapproved by the Securities and
   Exchange Commission nor has the Securities and Exchange Commission or any
      State Securities Commission passed upon the accuracy or adequacy of
   this prospectus. Any representation to the contrary is a criminal offense.

                            -----------------------


           The date of this prospectus supplement is August 11, 2000.