Exhibit 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statement on Form S‑4 (No. 333-107098) and Registration Statements on Forms S-8 (Nos. 333-110432, 333-128339, 333-152456, 333-140817 and 333-170133) of Biogen Idec Inc. of our reportdated February 4, 2015 relating to the financial statements and the effectiveness of internal control over financial reporting, which appears in this Form 10‑K.

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

February 4, 2015