Type I hypersensitivity to rubber. Seven patients with type I hypersensitivity reactions to rubber are reported. Radioallergosorbent testing with crude latex antigen was positive in 6/7 patients. Five patients had coexisting spina bifida, and all had undergone surgery before the development of rubber allergy. Rubber allergy is a new phenomenon that should be in the differential diagnosis of idiopathic anaphylaxis and urticaria. 