Item 5.02. Departure of Directors or Certain Officers; Election of Directors;
Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On November 11, 2008, Alexion Pharmaceuticals, Inc., or Alexion, announced that David W. Keiser, Alexion's Chief Operating Officer since 1992 and President since 2002, will retire by the end of 2008. Mr. Keiser's responsibilities will be distributed among current members of Alexion's senior management reporting to Leonard Bell, M.D., Chief Executive Officer of Alexion.

Mr. Keiser will remain on Alexion's Board of Directors at least through the expiration of his current term in 2009 and will be available to consult with management and the Board in the future.

A copy of the press release announcing Mr. Keiser's retirement has been filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

99.1 Press Release issued by Alexion Pharmaceuticals, Inc. on November 11, 2008 relating to the retirement of Mr. David W. Keiser.

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