We report a case of cardiovascular collapse in a homozygous sickle cell patient undergoing elective orthopaedic surgery, following the intravenous administration of cefuroxime. This patient had no known previous drug allergies. She had been taking prophylactic penicillin V on a daily basis, for 10 years and had encountered no problems. She had received cefuroxime on at least four previous occasions, for the treatment of chest infections, with no reported problems. Her serum mast cell tryptase, 1 h after the onset of anaphylaxis, was greater than 200 microg x l(-1) (normal range 10-16). She was skin prick tested, 6 weeks after the event, to all the drugs administered during the course of the anaesthetic and reacted positively only to cefuroxime. Specific IgE levels for penicillin determinants and latex were negative (13 and 0 IU x ml(-1), respectively UniCAP Pharmacia & Upjohn).