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                                 March 11, 1998


Securities and Exchange Commission
ATTN: Karen Garnett, Esq.
450 Fifth Street, N.W.
Judiciary Plaza
Washington, D.C. 20549

                ON FORM S-3 OF 2,300,000 SHARES OF COMMON STOCK
                (REGISTRATION NO. 333-46767)

Ladies and Gentlemen:

        On behalf of IDEC Pharmaceuticals Corporation (the "Company"), we hereby
request the above-referenced Registration Statement, originally filed with the
Commission on February 24, 1998 and amended on March 2, 1998, be withdrawn. The
Company is requesting a withdrawal of the Registration Statement due to
unanticipated market factors. Furthermore, the Company has neither sold nor made
any offers to sell any of the shares covered by such Registration Statement.

        Please provide the Company with a copy of the order granting withdrawal
of the Registration Statement as soon as it is available.

        If you have any questions regarding this application, please do not
hesitate to contact the Company's legal counsel, J. Stephan Dolezalek of
Brobeck, Phleger & Harrison LLP, at (650) 496-2842 or, in his absence, Kimberley
E. Henningsen at (650) 496-2640.

                                        Very truly yours,

                                        IDEC PHARMACEUTICALS CORPORATION

                                        /s/ WILLIAM H. RASTETTER
                                        William H. Rastetter, Ph.D.

cc:     Distribution List