Total intravenous anaesthesia with ketamine-propofol offers distinct advantages over a TIVA with an opiate, including less cardiovascular and respiratory depression and an altered neuroendocrine and immunological stress response pattern. The effects of the more active stereoisomer S-(+)-ketamine in combination with propofol on the circulatory, endocrine and metabolic responses to abdominal surgery were compared with those of alfentanil-propofol. Twenty-four patients scheduled for elective hysterectomy participated in this study which had the approval of our institution's ethics committee. Anaesthesia was induced with 2 mg/kg S-(+)-ketamine or 0.05 mg/kg alfentanil, followed by 1 mg/kg propofol. Tracheal intubation was facilitated with 0.06 mg/kg vecuronium. Anaesthesia was maintained with 1 mg/kg per h S-(+)-ketamine or 0.0125 mg/kg per h alfentanil and propofol at an initial rate of 15 mg/kg per h which was reduced to 5 mg/kg per h after 30 min. Blood samples for catecholamines, cortisol and metabolites were drawn at predetermined times from before induction to 6 h postoperatively. Adrenaline and noradrenaline concentrations decreased preoperatively in the ketamine group (K) from 55 to 29 pg/ml and 166 to 39 pg/ml, respectively, and then increased to postoperative maxima of 193 or 315 pg/ml. A similar pre and postoperative course was seen in the alfentanil group (A) with slightly lower (P < 0.05) intraoperative concentrations in A. Cortisol concentrations increased in K from 12 micrograms/dl to 34 micrograms/dl intraoperatively and further to a maximum of 42 micrograms/dl postoperatively. The intraoperative increase was attenuated in A and the difference between the groups was significant (P < 0.0001). The initial ketamine bolus and tracheal intubation caused a marked, transient increase of mean arterial blood pressure from the baseline value of 105 mmHg to 120 mmHg with a subsequent decrease to 88 mmHg prior to skin incision and a gradual return to baseline during surgery. TIVA with ketamine-propofol had little effect on the perioperative courses of the endocrine parameters, which behaved as they do under anesthesia with isoflurane-nitrous oxide. Plasma catecholamine concentrations were not elevated in the period between induction of anaesthesia and skin incision.