Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statement on Form S-8 (No. 333-87421) of Cephalon, Inc., of our report dated June 28, 2005 relating to the financial statements of the Cephalon, Inc. 401(k) Profit Sharing Plan, which appears in this Form 11-K.

PricewaterhouseCoopers LLP

Philadelphia, PA

June 28, 2005