Prospectus Supplement No. 20                    Filed pursuant to Rule 424(b)(3)
to Prospectus dated August 6, 2001              File No. 333-62234

                                 CEPHALON, INC.

           $400,000,000 5 1/4% CONVERTIBLE SUBORDINATED NOTES DUE 2006

         This document supplements information contained in that certain
prospectus of Cephalon, Inc. dated August 6, 2001, as amended and supplemented
from time to time, relating to the potential resale from time to time of
$400,000,000 5 1/4% Convertible Subordinated Notes due 2006 and 5,405,405 shares
of common stock by the selling securityholders identified in the prospectus and
any prospectus supplements. This prospectus supplement is not complete without,
and may not be delivered or utilized except in connection with the prospectus,
including any amendments or supplements thereto.

         The following table supplements, or amends, as noted, the information
set forth in the prospectus under the caption "Selling Securityholders" with
respect to:

         -        the principal amount of notes beneficially owned by each
                  selling securityholder and the maximum principal amount that
                  each may offer, and

         -        the number of shares of common stock issued upon conversion of
                  the notes that each selling securityholder may sell under the
                  prospectus, as amended or supplemented.



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                                                                                            NUMBER OF COMMON
                                                                   PRINCIPAL AMOUNT OF     SHARES ISSUED UPON
                                                                   NOTES BENEFICIALLY    CONVERSION THAT MIGHT
                                                                        OWNED (2)               BE SOLD
NAME OF SELLING SECURITYHOLDER (1)
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The following information supplements the information
set forth in the prospectus originally filed or as
previously amended or supplemented:
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MFS Total Return Fund                                                  1,500,000                 20,270
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(1) The information set forth herein is as of October 8, 2002 and will be
updated as required.

(2) Beneficial ownership is determined in accordance with the rules of the SEC
and generally includes voting or investment power with respect to securities.

         Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
adequacy or accuracy of this prospectus supplement. Any representation to the
contrary is a criminal offense.

           The date of this prospectus supplement is October 8, 2002.