The pharmacokinetics of droperidol were studied in 42 surgical patients using doses of 5, 10 and 15 mg i.v., in association with neuroleptanalgesia or volatile anaesthetics. Plasma concentrations of droperidol were measured by radioimmunoassay. During neuroleptanalgesia, droperidol kinetics were linear over the dose range tested: the overall mean elimination half-life was 127 min, Vdss 103 litre and the plasma clearance 732 ml min-1. The kinetics of droperidol were similar under neuroleptanalgesia and under anaesthesia with halothane or enflurane. There was no significant correlation between the volume of distribution or clearance with age (14-65 yr) or body weight (48-90 kg).