SCHEDULE 14A
                    Proxy Statement Pursuant to Section 14(a)
            of the Securities Exchange Act of 1934 (Amendment No. __)


Filed by the Registrant                     [ ]

Filed by a Party other than the Registrant  [x]

Check the appropriate box:

[ ] Preliminary Proxy Statement
[ ] Confidential, for Use of the Commission Only (as permitted by
    Rule 14a-6(e)(2))
[ ] Definitive Proxy Statement
[X] Definitive Additional Materials
[ ] Soliciting Material Pursuant to ss. 240.14a-12

                          IMCLONE SYSTEMS INCORPORATED

                (Name of Registrant as Specified In Its Charter)

                                  CARL C. ICAHN
                               ALEXANDER J. DENNER
                                PETER S. LIEBERT
                                 BARBERRY CORP.
                         HIGH RIVER LIMITED PARTNERSHIP
                                       AND
                             HOPPER INVESTMENTS LLC


    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (check the appropriate box):

[X] No fee required.

[ ] Fee computed on table below per Exchange Act Rule 14a-6(i)(4) and 0-11.

     1)   Title of each class of securities to which transaction applies:

     2)   Aggregate number of securities to which transaction applies:

     3)   Per unit  price  or other  underlying  value of  transaction  computed
          pursuant to Exchange  Act Rule 0-11 (set forth the amount on which the
          filing fee is calculated and state how it was determined):

     4)   Proposed maximum aggregate value of transaction:

     5)   Total fee paid:

[ ] Fee paid previously with preliminary materials.

[ ] Check box if any part of the fee is offset as provided  by  Exchange  Act
    Rule  0-11(a)(2)  and identify the filing for which the  offsetting fee was
    paid  previously.  Identify the previous filing by  registration  statement
    number, or the Form or Schedule and the date of its filing.

     1)   Amount Previously Paid:

     2)   Form, Schedule or Registration Statement No.:

     3)   Filing Party:

     4)   Date Filed:





The  attached  letter is being  delivered  to  stockholders  of ImClone  Systems
Incorporated.






                                                                       EXHIBIT 1

                                  Carl C. Icahn
                          767 Fifth Avenue, 47th Floor
                            New York, New York 10153


October 17, 2006

Dear Fellow Stockholders of ImClone Systems Incorporated:

I am soliciting  your written  consents:  (1) to remove Vincent T. DeVita,  Jr.,
John A. Fazio,  Joseph L.  Fischer and William R. Miller (the "Four  Directors")
from ImClone's Board; and (2) to appoint Peter S. Liebert as a director.

We  believe  the best path for  ImClone  is the  removal  of the four  directors
mentioned  above.  Each of these directors has been a member of the Board during
the last three years, a period during which the stock price declined from a high
of $86 (1) per share to its present price of $30 per share. In our opinion,  the
Four Directors and their  colleagues on the Board seriously  damaged the company
in ways we will explain below. Furthermore, we believe that, if we do not remove
these four  directors,  obtaining a new CEO of the caliber ImClone needs will be
extremely difficult if not impossible because such a CEO will not wish to report
to a Board  some of whose  members  are  responsible  for the many  failures  in
judgment made during the last few years.

Below, we highlight two of the many missteps of the pre-September  2006 Board of
Directors.

     1.)  Failing to cause ImClone to pursue an aggressive  development  program
          for Erbitux.

On February 12, 2004,  Erbitux was approved by the FDA. It is inexcusable  that,
since that time, the Board did not insist on conducting  first-line colon cancer
clinical trials.  In our view obtaining this first-line  approval would not only
have been extremely  profitable to ImClone but, in addition,  would have widened
the gap  between  ImClone  and its  competitors  such  as  Amgen.  Additionally,
positive results from such trials could potentially have helped suffering cancer
patients.  What is  inexplicable  is that more than two years have gone by since
the original  approval,  and the company must now depend on the National  Cancer
Institute, which luckily chose to fund a trial in this first-line indication. We
assume that they conducted this first-line trial because ImClone was not running
an appropriate trial. Most importantly, any potential benefit to cancer patients
was lost because the Board failed to act.

     2.)  The Board has allowed Erbitux's competitive lead to shrink.

Over the past two years,  other competing  drugs in the same class,  called EGFR
antibodies,  have advanced in clinical development more rapidly than Erbitux. We
blame the Board,  which  includes the Four Directors for failing to maintain the
overwhelming  lead that Erbitux once enjoyed.  Although Erbitux still has a lead
over its competitors, that lead has shrunk meaningfully and without our proposed
changes to the Board and the hiring of the right CEO,  ImClone,  in our opinion,
will continue to fall behind.

One of the major  reasons for  ImClone's  problems is that in the past few years
ImClone has not had a CEO with biotechnology experience. Inexplicably, the Board
continues to hire CEOs  failing to have this  qualification.  The  pre-September
2006 Board has been  responsible  for hiring a string of CEOs who failed to act.
Even more  concerning,  is that  several  weeks ago,  the Board  entered  into a
multi-million  dollar  contract  extension  with the current CEO whose  previous
positions  were  at  consumer  products  companies  and  who  has  no  research,
development,  or drug commercialization  experience. The Board insists on making
the same damaging errors and certainly has not learned from its past mistakes.

- --------
(1) The stock price was over $86.00 on July 1, 2004.


It is my belief that  companies  function  best when they are run by a competent
CEO who understands the business,  sets goals, and most importantly  understands
that he is accountable to a Board he respects.  One of my affiliated  companies,
American  Real Estate  Partners LP, which trades on the New York Stock  Exchange
(ACP),  has a number of different  businesses and it employs  different CEOs for
each line of business.  Each is a good leader and each is held  accountable  for
the business  that he runs.  As you can see from its stock  price,  ACP has done
extremely  well during the same period  that  Imclone's  stock has hit a high of
about $86 and is currently $30. If the Four Directors are removed by you and Dr.
Leibert is added, the new Board will endeavor to promptly get a top CEO who will
understand the business,  understand the goals, and understand that he or she is
accountable to the Board.

How have the Four Directors fared as a result of being at ImClone? Since July 1,
2003,  Vincent DeVita has netted  approximately $2.8 million from selling stock,
John Fazio netted  approximately  $460,000 from selling stock and William Miller
netted  approximately  $420,000  from selling  stock.  Also,  in  aggregate  the
directors to be removed collectively report holding more than 800,000 shares and
options,  which we believe, for the most part, were given to them by ImClone. In
addition,  Mr.  Fischer,  the current CEO (and a Board  member  since  September
2003),  receives cash compensation of approximately  $87,000 per month in salary
and bonus.  The Four  Directors  have not  exactly  shared in the bad fortune of
ImClone's shareholders.  It is not surprising that they want to hold on to their
positions as directors.

But we do agree with the directors to be removed on at least one thing. In their
letter, they stated that the company has "good long-term  prospects" and Erbitux
"studies are on track to begin to deliver  results" at the end of this year.  We
agree;  but if they  believe  in the  company,  we wonder why (1) they have been
selling stock rather than buying and (2) they have vociferously  complained that
we were  opposed to selling  the  company at $36 per share.  This  contradictory
message is just another  manifestation  of the confusion that emanates from this
pre-September 2006 Board. This confusion must end. Remove the Four Directors who
share the blame for the company's missteps and lost opportunities.

We  believe in  ImClone.  We have been  buyers,  not  sellers.  It is time for a
change. We must get a new CEO and this will not happen until the directors to be
removed leave the Board.  Fast action is needed.  We need your help. Please sign
and return the  consent  form as  quickly  as  possible  in order to help us get
ImClone back on track without delay.

WE  BELIEVE  THAT YOUR  VOICE IN THE  FUTURE OF  IMCLONE  CAN BEST BE  EXPRESSED
THROUGH YOUR CONSENT TO THE TWO PROPOSALS OUTLINED ABOVE. WE URGE YOU TO PROTECT
YOUR  INVESTMENT  IN IMCLONE NOW BY SIGNING,  DATING AND  RETURNING THE ENCLOSED
WHITE CONSENT CARD TODAY.


Very truly yours,


/s/ Carl Icahn
- --------------
Carl Icahn