EXHIBIT 23(a)


                    CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS



As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement of our report dated August 28, 1998
included in Alexion Pharmaceuticals, Inc.'s Form 10-K for the year ended 
July 31, 1998 and to all references to our Firm included in this registration
statement.

                                              /S/ ARTHUR ANDERSEN LLP

                                                  ARTHUR ANDERSEN LLP


Hartford, Connecticut
February 3, 1999