Postoperative pain relief with epidural morphine or buprenorphine and intramuscular morphine was investigated in 67 patients undergoing hepatectomy. When the patient first complained of pain after surgery, 1 or 2mg of epidural morphine, or 0.06 mg of epidural buprenorphine given either at T 10-11 or L 3-4, or 0.1 mg/kg of morphine intramuscularly was administered. Lumbar epidural morphine 2mg, as well as thoracic epidural morphine 2mg, produced excellent and long-lasting pain relief. Nine of 12 patients receiving thoracic epidural buprenorphine 0.06 mg were completely pain-free. Thoracic epidural morphine 1 mg and lumbar epidural buprenorphine 0.06 mg produced incomplete analgesia. Analgesic duration of intramuscular morphine tended to be shorter than that of 2 mg of epidural morphine. PaCO2 increased significantly following thoracic epidural morphine 2 mg, although PaCO2 did not change after lumbar epidural morphine 2 mg. No patient had serious side effects. The lumbar epidural administration of 2 mg morphine may be recommended for postoperative analgesia following hepatectomy.