On April 30, 2008, Alexion issued a press release relating to its results of operations and financial conditions for the quarter ended March 31, 2008. A copy of the press release is furnished as Exhibit 99.1 to this form 8-K.

The attached press release contains both U.S. Generally Accepted Accounting Principles (“GAAP”) and non-GAAP financial measures. The non-GAAP financial measures exclude share-based compensation expenses. Reconciliations between non-GAAP and GAAP financial measures are included in the press release set forth as Exhibit 99.1 furnished to this form 8-K. The Company’s management utilizes non-GAAP financial information to provide a useful measure of comparative operating performance of the Company. The non-GAAP financial measures are supplemental to and not a substitute for, measures of financial performance prepared in accordance with GAAP.

(d) Exhibits

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.