James C. Mullen, president and chief executive officer of Biogen Idec, will retire from his position effective June 8, 2010. Mr. Mullen will also retire from the company’s board following his current term as director at the 2010 annual shareholder meeting. The company is actively searching for a successor to Mr. Mullen.

“Jim Mullen’s more than 20 years of leadership have transformed Biogen Idec from a fledgling company with no marketed products to a global leader in the biotech industry that has helped hundreds of thousands of patients worldwide,” said Biogen Idec chairman William D. Young. “His vision and commitment to our patients, investors and employees resulted in the successful merger of Biogen and Idec in 2003, three blockbuster products, and a broad and deep pipeline that holds the promise of more great products in the future. We look forward to continuing to build on this success.”