A number of drugs used in cancer chemotherapy have produced hypersensitivity reactions. Generalized urticaria to cyclophosphamide has been reported previously in 5 cases. We have recently observed a ...25-year-old patient with M. Hodgkin who developed an anaphylactic shock immediately following an intravenous infusion of cyclophosphamide. Total serum IgE was significantly elevated (1280 U/ml). Using the epicutan skin testing highly positive papulo-vesicular reaction to cyclophosphamide was observed.