Cephalon (CEPH) 10-Q 2010 Q3 Quarterly report

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Report of Cephalon, Inc. (the “Company”) on Form 10-Q for the period ended September 30, 2010, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, J. Kevin Buchi, Chief Operating Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, based on my knowledge, that:

(1)The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of the Company.

/s/ J. Kevin Buchi

J. Kevin Buchi

Chief Operating Officer

October 29, 2010