The analgesic efficacy and side-effects of combined epidural infusion of bupivacaine and morphine, in comparison with these drugs alone, for postoperative analgesia after hysterectomy (60 patients) were evaluated. Before general anaesthesia, all patients had an epidural catheter placed (Th11-12) and 20 ml of 0.5%, bupivacaine was injected. In random order, epidural infusion was continued for 24 h with either 0.25% bupivacaine 4 ml.h-1 (BUPI-group), a bolus of 2 mg of morphine followed by morphine 0.2 mg.h-1 (MO-group), or a combination of the two drugs (COMB-group). A urinary bladder catheter was kept for 24 h. Supplementary postoperative pain medications were i.m. morphine 0.1 mg.kg-1 or rectal indomethacin 50 mg, on request. Immediately after awakening from general anaesthesia and transfer to the recovery room, 18/20 of the BUPI-group patients, 17/20 of the MO-group patients and 19/20 of the COMB-group patients were pain-free. In the postoperative evening and the first postoperative morning, the corresponding figures were 7/20 and 10/20 in the BUPI-group, 15/20 and 15/20 in the MO-group, and 18/20 and 15/20 in the COMB-group (postop, evening; P less than 0.01 BUPI vs. others). The number of patients requiring supplementary analgesics (morphine and indomethacin during the first 24 h was greatest in the BUPI-group P less than 0.01). The number of patients who vomited during the 24-h period was 3 in the BUPI-group, 9 in the MO-group and 5 in the COMB-group.(ABSTRACT TRUNCATED AT 250 WORDS)