Recurrent idiopathic anaphylaxis is an illness consisting of recurring anaphylactic or anaphylactoid attacks of unknown cause. A patient has been described whose attacks appeared to be associated with endogenous progesterone secretion and who was treated successfully with an analog of luteinizing hormone-releasing hormone (LHRH). This report summarizes the treatment of four additional women with recurrent anaphylaxis in a randomized, double-blind trial of an LHRH agonist and placebo. Two out of the four women experienced remission of their symptoms with the LHRH analog. The patients who responded to therapy had experienced systemic anaphylactoid reactions after provocation with an LHRH infusion and the intradermal injection of medroxyprogesterone; the nonresponders had no adverse reactions to either challenge. Ovarian suppression with LHRH agonist may benefit a subset of women with recurrent idiopathic anaphylaxis.