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

Mr. Patrice Coissac, Senior Vice President of Alexion Pharmaceuticals, Inc. and President of Alexion Pharma International Sārl, Alexion's subsidiary located in Lausanne, Switzerland, will retire from Alexion effective February 8, 2013. Mr. Coissac joined Alexion in November 2005 as Senior Vice President and President of Alexion Europe SAS and has served as President of Alexion Pharma International Sārl since April 2009.

Mr. Coissac's responsibilities have been assumed by Mr. Frank Wright, who joined Alexion as Senior Vice President in December 2012. Mr. Wright will also be appointed the President of Alexion Pharma International Sārl.

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Signature Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: January 25, 2013 ALEXION PHARMACEUTICALS, INC.

By: /s/ Michael V. Greco Name: Michael V. Greco Title: Associate General Counsel and Corporate Secretary