SC TO-I/A

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE TO
Tender Offer Statement under Section 14(d)(1) or 13(e)(1) of the Securities Exchange Act of 1934

(Amendment No. 4 - Final Amendment)

CEPHALON, INC.
(Name of Subject Company (issuer))

CEPHALON, INC.
(Name of Filing Person (issuer))

2¹/2% Convertible Subordinated Notes
due December 2006
(Title of Class of Securities)

156708AD1 and 156708AE9
(CUSIP Numbers of Class of Securities)

John E. Osborn
Senior Vice President, General Counsel and Secretary
Cephalon, Inc.
41 Moores Road
Frazer, PA 19355
(610) 344-0200
(Name, Address and Telephone Number of Person Authorized to Receive
Notices and Communications on Behalf of the Person(s) Filing Statement)

Copy to:
Pran Jha
Sidley Austin Brown & Wood LLP
Bank One Plaza
10 South Dearborn Street
Chicago, IL 60603

o Check box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes to designate any transactions to which this statement relates:

o third party tender offer subject to Rule 14d-1	o going-private transaction subject to Rule 13e-3
ý issuer tender offer subject to Rule 13e-4	o amendment to Schedule 13D under Rule 13d-2

Check the following box if the filing is a final amendment reporting the results of the tender offer. ý

        This Amendment No. 4 to Tender Offer Statement on Schedule TO amends and supplements the Tender Offer Statement on Schedule TO (as amended and supplemented, the "Schedule TO") filed by Cephalon, Inc., a Delaware corporation (the "Company"), on June 10, 2005, relating to an offer by the Company to purchase for cash any and all of the Company's outstanding 2¹/2% Convertible Subordinated Notes due December 2006 (the "Notes") upon the terms and subject to the conditions contained in the Offer to Purchase dated June 10, 2005 (as amended or supplemented from time to time, the "Offer to Purchase"), a copy of which is attached hereto as Exhibit (a)(1)(i), and the related Letter of Transmittal (the "Letter of Transmittal"), a copy of which is attached hereto as Exhibit (a)(1)(ii) (which together with the Offer to Purchase constitutes the "Offer").

Item 11. Additional Information.

        Item 11 of the Schedule TO is hereby amended and supplemented by adding the following information:

        The Offer expired at 5:00 p.m., New York City time, on July 11, 2005. As of the expiration date of the Offer, $511,743,000 principal amount of Notes, representing approximately 98.1 percent of Notes outstanding, had been properly tendered and not validly withdrawn pursuant to the Offer, all of which were accepted for purchase by the Company. On July 12, 2005, the Company issued a press release announcing the acceptance for purchase of Notes tendered pursuant to the Offer, a copy of which is filed as an exhibit hereto and incorporated herein by reference.

Item 12. Exhibits.

        Item 12 of the Schedule TO is hereby amended and restated in its entirety as follows:

Exhibit No.	Description
(a)(1)(i)*	Offer to Purchase, dated June 10, 2005.
(a)(1)(ii)*	Form of Letter of Transmittal.
(a)(1)(iii)*	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and other Nominees.
(a)(1)(iv)*	Form of Letter to Clients.
(a)(1)(v)*	Form of Notice of Guaranteed Delivery.
(a)(1)(vi)*	Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9.
(a)(2)	None.
(a)(3)	None.
(a)(4)	None.
(a)(5)*	Press Release, dated June 10, 2005.
(a)(5)(A)	Press Release, dated June 13, 2005, included as Exhibit 99.1 to the Company's Current Report on Form 8-K dated June 15, 2005, is hereby incorporated by reference.
(a)(5)(B)	Press Release, dated June 14, 2005, included as Exhibit 99.3 to the Company's Current Report on Form 8-K dated June 15, 2005, is hereby incorporated by reference.
(a)(5)(C)+	Press Release, dated July 12, 2005.
(b)	None.
(d)(1)	Amended and Restated Rights Agreement, dated as of January 1, 1999, between the Company and StockTrans, Inc., included as Exhibit 1 to the Company's Form 8-A/A (12G) filed January 20, 1999, is hereby incorporated by reference.
(d)(2)	First Amendment to Amended and Restated Rights Agreement, dated July 31, 2000, between the Company and StockTrans, Inc., included as Exhibit 1 to the Company's Form 8-A/12G filed on August 2, 2000, is hereby incorporated by reference.
(d)(3)	Second Amendment to Amended and Restated Rights Agreement, dated October 27, 2003, between the Company and StockTrans, Inc., included as Exhibit 1 to the Company's Form 8-A/12G on October 27, 2003, is hereby incorporated by reference.
(d)(4)	Indenture, dated as of December 11, 2001, between the Company and State Street Bank and Trust Company, included as Exhibit 4.1 to the Company's Registration Statement on Form S-3 (Registration No. 333-82788) filed on February 14, 2002, is hereby incorporated by reference.
(d)(5)	Indenture, dated as of June 11, 2003, between the the Company and U.S. Bank National Association, included as Exhibit 4.1 to the Company's Quarterly Report on Form 10-Q for the period ended June 30, 2003, is hereby incorporated by reference.

2

(d)(6)	Registration Rights Agreement, dated as of June 11, 2003, between the Company and Credit Suisse First Boston LLC, CIBC World Markets Corp., J.P. Morgan Securities Inc., Morgan Stanley & Co. Incorporated, SG Cowen Securities Corporation, ABN AMRO Rothschild LLC, Citigroup Global Markets Inc. and Lehman Brothers Inc., included as Exhibit 10.4 to the Company's Quarterly Report on Form 10-Q for the period ended June 30, 2003, is hereby incorporated by reference.
(d)(7)	Indenture, dated as of December 20, 2004, between the Company and U.S. Bank National Association, included as Exhibit 4.l to the Company's Current Report on Form 8-K dated December 21, 2004, is hereby incorporated by reference.
(d)(8)	Registration Rights Agreement, dated as of December 20, 2004, between the Company and U.S Bank National Association, included as Exhibit 4.2 to the Company's Current Report on Form 8-K dated December 21, 2004, is hereby incorporated by reference.
(d)(9)	Indenture, dated June 7, 2005, between the Company and U.S. Bank, National Association, included as Exhibit 4.1 to the Company's Current Report on Form 8-K dated June 8, 2005, is hereby incorporated by reference.
(d)(10)	Five Year Convertible Note Hedge, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(1) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(11)	Seven Year Convertible Note Hedge, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(2) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(12)	Five Year Warrant, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(3) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(13)	Seven Year Warrant, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(4) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(14)	Five Year Convertible Note Hedge, dated December 3, 2004, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(5) to Amendment No. 1 to the Company's Tender Offer Statement on Schedule TO filed December 14, 2004, is hereby incorporated by reference.
(d)(15)	Seven Year Convertible Note Hedge, dated December 3, 2004, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(5) to Amendment No. 1 to the Company's Tender Offer Statement on Schedule TO filed December 14, 2004, is hereby incorporated by reference.
(d)(16)	Hedge Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.1 to the Company's Current Report on Form 8-K filed June 8, 2005, is hereby incorporated by reference.
(d)(17)	Warrant Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.2 to the Company's Current Report on Form 8-K filed June 8, 2005, is hereby incorporated by reference.
(d)(18)*	Description of the Amended and Restated Rights Agreement from Item 1 of the Company's Form 8-A/A (12G) filed January 20, 1999.
(d)(19)*	Description of the First Amendment to Amended and Restated Rights Agreement from Item 1 of the Company's Form 8-A/12G filed on August 2, 2000.
(d)(20)*	Description of the Second Amendment to Amended and Restated Rights Agreement from Item 1 of the Company's Form 8-A/12G filed on October 27, 2003.
(d)(21)*	Description of Notes section (pages 18 through 28) of Amendment No. 2 to the Company's Registration Statement on Form S-3 (Registration No. 333-82788) filed on May 14, 2002.
(d)(22)*	Description of Notes section (pages 18 through 28) of Amendment No. 1 to the Company's Registration Statement on Form S-3 (Registration No. 333-108320) filed December 3, 2003.
(d)(23)*	Description of the Convertible Note Hedges and Warrants from Item 5 of the Company's Tender Offer Statement on Schedule TO filed November 16, 2004.
(d)(24)*	Description of the Convertible Note Hedges from Item 5 of Amendment No. 1 to the Company's Tender Offer Statement on Schedule TO filed December 14, 2004.
(d)(25)	Amendment to Hedge Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.1 to the Company's Current Report on Form 8-K filed July 7, 2005, is hereby incorporated by reference.

3

(d)(26)	Hedge Confirmation dated as of June 28, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.2 to the Company's Current Report on Form 8-K filed July 7, 2005, is hereby incorporated by reference.
(d)(27)	Amendment to Warrant Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.3 to the Company's Current Report on Form 8-K filed July 7, 2005, is hereby incorporated by reference.
(g)	None.
(h)	None.

*

Previously filed.

+

Filed herewith.

4

SIGNATURE

        After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

	Cephalon, Inc.
	By:	/s/  JOHN E. OSBORN Name: John E. Osborn Title:  Senior Vice President, General Counsel and Secretary
Dated: July 12, 2005

5

Exhibit Index

Exhibit No.	Description
(a)(1)(i)*	Offer to Purchase, dated June 10, 2005.
(a)(1)(ii)*	Form of Letter of Transmittal.
(a)(1)(iii)*	Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies and other Nominees.
(a)(1)(iv)*	Form of Letter to Clients.
(a)(1)(v)*	Form of Notice of Guaranteed Delivery.
(a)(1)(vi)*	Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9.
(a)(2)	None.
(a)(3)	None.
(a)(4)	None.
(a)(5)*	Press Release, dated June 10, 2005.
(a)(5)(A)	Press Release, dated June 13, 2005, included as Exhibit 99.1 to the Company's Current Report on Form 8-K dated June 15, 2005, is hereby incorporated by reference.
(a)(5)(B)	Press Release, dated June 14, 2005, included as Exhibit 99.3 to the Company's Current Report on Form 8-K dated June 15, 2005, is hereby incorporated by reference.
(a)(5)(C)+	Press Release, dated July 12, 2005.
(b)	None.
(d)(1)	Amended and Restated Rights Agreement, dated as of January 1, 1999, between the Company and StockTrans, Inc., included as Exhibit 1 to the Company's Form 8-A/A (12G) filed January 20, 1999, is hereby incorporated by reference.
(d)(2)	First Amendment to Amended and Restated Rights Agreement, dated July 31, 2000, between the Company and StockTrans, Inc., included as Exhibit 1 to the Company's Form 8-A/12G filed on August 2, 2000, is hereby incorporated by reference.
(d)(3)	Second Amendment to Amended and Restated Rights Agreement, dated October 27, 2003, between the Company and StockTrans, Inc., included as Exhibit 1 to the Company's Form 8-A/12G on October 27, 2003, is hereby incorporated by reference.
(d)(4)	Indenture, dated as of December 11, 2001, between the Company and State Street Bank and Trust Company, included as Exhibit 4.1 to the Company's Registration Statement on Form S-3 (Registration No. 333-82788) filed on February 14, 2002, is hereby incorporated by reference.
(d)(5)	Indenture, dated as of June 11, 2003, between the the Company and U.S. Bank National Association, included as Exhibit 4.1 to the Company's Quarterly Report on Form 10-Q for the period ended June 30, 2003, is hereby incorporated by reference.
(d)(6)	Registration Rights Agreement, dated as of June 11, 2003, between the Company and Credit Suisse First Boston LLC, CIBC World Markets Corp., J.P. Morgan Securities Inc., Morgan Stanley & Co. Incorporated, SG Cowen Securities Corporation, ABN AMRO Rothschild LLC, Citigroup Global Markets Inc. and Lehman Brothers Inc., included as Exhibit 10.4 to the Company's Quarterly Report on Form 10-Q for the period ended June 30, 2003, is hereby incorporated by reference.
(d)(7)	Indenture, dated as of December 20, 2004, between the Company and U.S. Bank National Association, included as Exhibit 4.l to the Company's Current Report on Form 8-K dated December 21, 2004, is hereby incorporated by reference.
(d)(8)	Registration Rights Agreement, dated as of December 20, 2004, between the Company and U.S Bank National Association, included as Exhibit 4.2 to the Company's Current Report on Form 8-K dated December 21, 2004, is hereby incorporated by reference.
(d)(9)	Indenture, dated June 7, 2005, between the Company and U.S. Bank, National Association, included as Exhibit 4.1 to the Company's Current Report on Form 8-K dated June 8, 2005, is hereby incorporated by reference.
(d)(10)	Five Year Convertible Note Hedge, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(1) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(11)	Seven Year Convertible Note Hedge, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(2) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(12)	Five Year Warrant, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(3) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.

(d)(13)	Seven Year Warrant, dated June 6, 2003, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(4) to the Company's Tender Offer Statement on Schedule TO filed November 16, 2004, is hereby incorporated by reference.
(d)(14)	Five Year Convertible Note Hedge, dated December 3, 2004, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(5) to Amendment No. 1 to the Company's Tender Offer Statement on Schedule TO filed December 14, 2004, is hereby incorporated by reference.
(d)(15)	Seven Year Convertible Note Hedge, dated December 3, 2004, between the Company and Credit Suisse First Boston International, included as Exhibit (d)(5) to Amendment No. 1 to the Company's Tender Offer Statement on Schedule TO filed December 14, 2004, is hereby incorporated by reference.
(d)(16)	Hedge Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.1 to the Company's Current Report on Form 8-K filed June 8, 2005, is hereby incorporated by reference.
(d)(17)	Warrant Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.2 to the Company's Current Report on Form 8-K filed June 8, 2005, is hereby incorporated by reference.
(d)(18)*	Description of the Amended and Restated Rights Agreement from Item 1 of the Company's Form 8-A/A (12G) filed January 20, 1999.
(d)(19)*	Description of the First Amendment to Amended and Restated Rights Agreement from Item 1 of the Company's Form 8-A/12G filed on August 2, 2000.
(d)(20)*	Description of the Second Amendment to Amended and Restated Rights Agreement from Item 1 of the Company's Form 8-A/12G filed on October 27, 2003.
(d)(21)*	Description of Notes section (pages 18 through 28) of Amendment No. 2 to the Company's Registration Statement on Form S-3 (Registration No. 333-82788) filed on May 14, 2002.
(d)(22)*	Description of Notes section (pages 18 through 28) of Amendment No. 1 to the Company's Registration Statement on Form S-3 (Registration No. 333-108320) filed December 3, 2003.
(d)(23)*	Description of the Convertible Note Hedges and Warrants from Item 5 of the Company's Tender Offer Statement on Schedule TO filed November 16, 2004.
(d)(24)*	Description of the Convertible Note Hedges from Item 5 of Amendment No. 1 to the Company's Tender Offer Statement on Schedule TO filed December 14, 2004.
(d)(25)	Amendment to Hedge Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.1 to the Company's Current Report on Form 8-K filed July 7, 2005, is hereby incorporated by reference.
(d)(26)	Hedge Confirmation dated as of June 28, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.2 to the Company's Current Report on Form 8-K filed July 7, 2005, is hereby incorporated by reference.
(d)(27)	Amendment to Warrant Confirmation dated as of June 2, 2005 by and among the Company, Deutsche Bank AG, New York and Deutsche Bank AG, London, included as Exhibit 10.3 to the Company's Current Report on Form 8-K filed July 7, 2005, is hereby incorporated by reference.
(g)	None.
(h)	None.

*

Previously filed.

+

Filed herewith.

EX-99.(A)(5)(C)

Exhibit 99(a)(5)(C)

News

Investor Contact: Chip Merritt
610-738-6376
cmerritt@cephalon.com

Media Contact: Robert W. Grupp
610-738-6402
rgrupp@cephalon.com

For Immediate Release

Cephalon, Inc. Accepts Notes Tendered Pursuant to Offer
for 2-1/2 Percent Convertible Subordinated Notes Due December 2006

Frazer, PA—July 12, 2005—Cephalon, Inc. (Nasdaq: CEPH) today announced that it has accepted notes tendered pursuant to its offer for all of its outstanding 2-1/2 Percent Convertible Subordinated Notes Due December 2006 (the "Notes"). The tender offer expired at 5:00 p.m. New York City time on July 11, 2005 (the "expiration date").

        As of the expiration date, $511,743,000 principal amount of the Notes, representing approximately 98 percent of the Notes outstanding, had been validly tendered and not withdrawn pursuant to the tender offer. Cephalon has accepted for purchase all Notes that have been validly tendered and not withdrawn. Each holder who tendered Notes on or before the expiration date will receive $975 in cash for each $1,000 principal amount of tendered Notes plus accrued but unpaid interest to, but not including, the date of payment.

        Deutsche Bank Securities Inc. acted as Dealer Manager in connection with the tender offer.

Cephalon, Inc.

        Founded in 1987, Cephalon, Inc. is an international biopharmaceutical company dedicated to the discovery, development and marketing of innovative products to treat sleep and neurological disorders, cancer and pain.

        Cephalon currently employs more than 2,300 people in the United States and Europe. U.S. sites include corporate headquarters in Frazer, Pennsylvania, and offices, research and development or manufacturing facilities in West Chester, Pennsylvania, Salt Lake City, Utah, and suburban Minneapolis, Minnesota. Cephalon's major European offices are located in Guildford, England, Martinsried, Germany, and in Maisons-Alfort, France.

        The company currently markets three proprietary products in the United States: PROVIGIL® (modafinil) Tablets [C-IV], GABITRIL® (tiagabine hydrochloride) and ACTIQ® (oral transmucosal fentanyl citrate) [C-II], and more than 20 products internationally. Further information about Cephalon and full prescribing information on its U.S. products is available at http://www.cephalon.com or by calling 1-800-896-5855.

SOURCE: Cephalon, Inc. • 145 Brandywine Parkway • West Chester, PA 19390-4245 • (610) 344-0300 • Fax (610) 344-0200 • Fax (610) 344-0981

In addition to historical facts or statements of current condition, this press release may contain forward-looking statements. Forward-looking statements provide Cephalon's current expectations or forecasts of future events. These may include statements regarding anticipated scientific progress on its research programs, development of potential pharmaceutical products, interpretation of clinical results, prospects for regulatory approval, manufacturing development and capabilities, market prospects for its products, yearly and quarterly sales and earnings guidance, and other statements regarding matters that are not historical facts. You may identify some of these forward-looking statements by the use of words in the statements such as "anticipate," "estimate," "expect," "project," "intend," "plan," "believe" or other words and terms of similar meaning. Cephalon's performance and financial results could differ materially from those reflected in these forward-looking statements due to general financial, economic, regulatory and political conditions affecting the biotechnology and pharmaceutical industries as well as more specific risks and uncertainties facing Cephalon such as those set forth in its reports on Form 8-K, 10-Q and 10-K filed with the U.S. Securities and Exchange Commission. Given these risks and uncertainties, any or all of these forward-looking statements may prove to be incorrect. Therefore, you should not rely on any such factors or forward-looking statements. Furthermore, Cephalon does not intend to update publicly any forward-looking statement, except as required by law.

# # #

SOURCE: Cephalon, Inc. • 145 Brandywine Parkway • West Chester, PA 19390-4245 • (610) 344-0300 • Fax (610) 344-0200 • Fax (610) 344-0981