Vancomycin is becoming increasingly used for prophylaxis, and treatment against resistant forms of penicillinase-producing staphylococci. This drug, and the aminoglycosides as a group, have serious side-effects and organ toxicity, and may interact with anaesthetic drugs, particularly muscle relaxants. Two cases of anaphylactoid reactions to vancomycin are reported. The first patient subsequently developed oliguria and marked oedema, while the second developed non-cardiogenic pulmonary oedema.