8-A12G

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                   FORM 8-A/A

                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                    PURSUANT TO SECTION 12(B) OR 12(G) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                                 CEPHALON, INC.
- --------------------------------------------------------------------------------
             (Exact Name of Registrant as Specified in Its Charter)

                  DELAWARE                                   23-2484489
- --------------------------------------------------           -------------------
(State of Incorporation or Organization)                     (I.R.S. Employer
                                                             Identification no.)

145 BRANDYWINE PARKWAY, WEST CHESTER, PENNSYLVANIA           19380
- --------------------------------------------------           -------------------
     (Address of Principal Executive Offices)                (Zip Code)


If this form relates to the registration of a class of securities pursuant
to Section 12(b) of the Exchange Act and is effective pursuant to General
Instruction A.(c), please check the following box. / /

If this form relates to the registration of a class of securities pursuant
to Section 12(g) of the Exchange Act and is effective pursuant to General
Instruction A.(d), please check the following box. /X/

Securities Act registration statement file number to which this form relates:
                               (If applicable)
Securities to be registered pursuant to Section 12(b) of the Act:


       Title of Each Class                   Name of Each Exchange on Which
       to be so Registered                   Each Class is to be Registered
       -------------------                   ------------------------------



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

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

Securities to be registered pursuant to Section 12(g) of the Act:

Preferred Stock Purchase Rights
- --------------------------------------------------------------------------------
                                (Title of Class)


- --------------------------------------------------------------------------------
                                (Title of Class)





Item 1. DESCRIPTION OF REGISTRANT'S SECURITIES TO BE REGISTERED.

     On July 31, 2000, the Company and StockTrans, Inc., as rights agent (the
"Rights Agent") entered into the First Amendment to Amended and Restated Rights
Agreement (the "Amendment") to the Amended and Restated Rights Agreement, dated
as of January 1, 1999, between the Company and the Rights Agent (the "Rights
Agreement"). The Amendment increases the initial "Purchase Price" (as defined in
the Rights Agreement) from $90.00 for each one one-hundredth of a share of
Series A Junior Participating Preferred Stock, par value $0.01 per share, of the
Company (the "Preferred Stock") purchasable upon the exercise of a Right (as
defined in the Right Agreement) to $200 for each one one-hundredth of a share of
Preferred Stock purchasable upon the exercise of a Right. The effective date of
the Amendment is July 31, 2000.

     The text of the Amendment is attached as Exhibit 1 and incorporated herein
by reference. The foregoing description of the Amendment is qualified in its
entirety by reference to Exhibit 1.

Item 2. EXHIBITS.

     1. First Amendment to Amended and Restated Rights Agreement, dated as of
July 31, 2000, between Cephalon, Inc. and StockTrans, Inc., as Rights Agent.





                                    SIGNATURE

     Pursuant to the requirements of Section 12 of the Securities and Exchange
Act of 1934, the registrant has duly caused this registration statement to be
signed on its behalf by the undersigned, thereunto duly authorized.

                                Cephalon, Inc.

Dated: July 31, 2000            By: /s/ FRANK BALDINO, JR.
                                    -------------------------------------------
                                    Name:  Frank Baldino, Jr.
                                    Title: Chairman and Chief Executive Officer

EX-1

EXHIBIT 1 - FIRST AMENDMENT TO AMENDED AND RESTATED RIGHTS AGREEMENT

                                 FIRST AMENDMENT
                                       TO
                              AMENDED AND RESTATED
                                RIGHTS AGREEMENT


     THIS FIRST AMENDMENT TO AMENDED AND RESTATED RIGHTS AGREEMENT (this
"Amendment") of the Rights Agreement (defined below) is made and entered as of
this the 31st day of July, 2000 between CEPHALON, INC. (the "Company"), and
STOCKTRANS, INC., as rights agent (the "Rights Agent").

     WHEREAS, the Company and Chemical Bank, as rights agent, were parties to a
Rights Agreement dated as of November 12, 1993, which was amended on November 1,
1998 to replace the existing rights agent with StockTrans, Inc. and was further
amended and restated by the Amended and Restated Rights Agreement, dated as of
January 1, 1999, between the Company and StockTrans, Inc. as Rights Agent (as
amended and restated, the "Rights Agreement");

     WHEREAS, pursuant to Section 27 of the Rights Agreement, the Company may,
and the Rights Agent shall, if the Company so directs, supplement or amend the
Rights Agreement without the approval of any holders of Rights (as defined in
the Rights Agreement);

     WHEREAS, the Company desires to amend the Rights Agreement in accordance
with Section 27 of the Rights Agreement as provided herein;

     NOW, THEREFORE, the Rights Agreement is hereby amended as follows:

     1. AMENDMENT OF SECTION 7(B).Section 7(b) of the Rights Agreement is hereby
amended and restated in its entirety to read as follows:

          "(b) The Purchase Price shall be initially $200 for each one-hundredth
     of a share of Preferred Stock purchasable upon the exercise of a Right. The
     Purchase Price and the number of one one-hundredth of a share of Preferred
     Stock or other securities or property to be acquired upon the exercise of a
     Right shall be subject to adjustment from time to time as provided in
     Sections 11 and 13 hereof and shall be payable in lawful money of the
     United States of America in accordance with paragraph (c) of this Section
     7."

     2. BINDING EFFECT. This Amendment shall be binding upon, and shall inure to
the benefit of, the parties hereto and their respective successors and assigns.







     3. EXECUTION IN COUNTERPARTS. This Amendment may be executed in
counterparts, each of which shall be deemed an original, but all of which shall
constitute one and the same instrument.

     4. GOVERNING LAW. This Amendment shall be governed by, and interpreted in
accordance with, the laws of the State of Delaware, without regard to principles
of conflict of laws.

     5. EFFECTIVENESS. Except as amended hereby, the Rights Agreement shall
remain in full force and effect and shall be otherwise unaffected hereby.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as of the day and year first above written.

                                 CEPHALON, INC.

                                 By:    /s/ FRANK BALDINO, JR.
                                     ---------------------------------------
                                 Name:  Frank Baldino, Jr.
                                 Title: Chairman and Chief Executive Officer

                                 STOCKTRANS, INC., Rights Agent

                                 By:    /s/ JONATHAN MILLER
                                     ---------------------------------------
                                 Name:  Jonathan Miller
                                 Title: President