CEPH Cephalon (MM)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C.  20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported)   July 21, 2011

Cephalon, Inc.

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code   (610) 344-0200

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨     Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨     Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨     Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨     Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01                                              Other Information .

(a)                                   On July 21, 2011, Cephalon, Inc. (the “Company”) completed its previously announced acquisition of ChemGenex Pharmaceuticals Limited (“ChemGenex”).  ChemGenex is now an indirect, wholly-owned subsidiary of the Company.

(b)                                  On July 21, 2011, the Company issued a press release announcing that the U.S. Food and Drug Administration approved the Risk Evaluation and Mitigation Strategy (REMS) for FENTORA® (fentanyl buccal tablet) [C-II] and ACTIQ® (oral transmucosal fentanyl citrate) [C-II].  The Company hereby incorporates by reference the press release dated July 21, 2011, attached hereto as Exhibit 99.1 and made a part of this Item 8.01.

Item 9.01                                              Financial Statements and Exhibits .

(d)                                              Exhibits .

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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EXHIBIT INDEX

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