Plasma concentrations of cortisol and glucose were measured from before to 9 h after skin incision in 24 patients undergoing abdominal hysterectomy. The patients were randomly allocated to receive either high-dose alfentanil anaesthesia (150 micrograms kg-1 initially, followed by continuous infusion at a rate of 3 micrograms kg-1 min-1) or neurolept anaesthesia (droperidol 0.25 mg kg-1 plus fentanyl 5 micrograms kg-1 initially, followed by intermittent incremental doses of fentanyl 50 micrograms). The intraoperative and initial postoperative increases in plasma cortisol and glucose concentrations were inhibited (P less than 0.05) by alfentanil but, later in the postoperative period, both groups showed identical increases in cortisol and glucose concentrations. Mean arterial pressure and heart rate were more stable in the alfentanil group. The concept of "stress-free" anaesthesia during high-dose opiate administration seems to be valid during operation and for the initial 1-3 h into the postoperative period.