A case of anaphylactic shock to pancuronium bromide is described in which a type I immunological reaction occurred. A 33-yr-old male anaesthetist, with no family or personal history of allergy, collapsed soon after induction of anaesthesia. The drugs used included fentanyl, droperidol, thiopentone and pancuronium. Diffuse erythema occurred, with probable cardiac arrest. The patient was treated with cardiac massage, sympathomimetics and cortisone, and made a complete recovery. Examination (skin tests, passive transfer according to Prausnitz and Küstner, in vitro lymphocyte transformation test, total IgE assay) revealed that the allergic reaction was to pancuronium bromide.