ARTHUR ANDERSEN LLP REPORT 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 30, 1996 included in Alexion Pharmaceuticals, Inc.'s Form 10-K for the year ended July 31, 1996 and to all references to our Firm included in this registration statement. /s/ ARTHUR ANDERSEN LLP Hartford, Connecticut July 15, 1997