Alexion Pharmaceuticals, Inc.
Leonard Bell, M.D.
Chief Executive Officer
(203) 272-2596

Makovsky + Company
David Patti (Media)
(212) 508-9623

Rx Communications
Rhonda Chiger (Investor)
(917) 322-2569

Alexion To Present At Bear Stearns Healthcare Conference

Cheshire, Conn, September 4, 2007 — Alexion Pharmaceuticals, Inc. (Nasdaq: ALXN) today announced that Dr. Leonard Bell, Chief Executive Officer of Alexion Pharmaceuticals, will present at the Bear Stearns 20th Annual Healthcare Conference in New York City at 8:00 a.m. ET on Tuesday, September 11, 2007.

An audio webcast of Dr. Bell’s remarks will be available live. You can access the webcast at: www.alexionpharm.com. An archived version of the remarks will also be available through the Company’s web site for a limited time following the conference.