We have evaluated the efficaciousness and side effects of continuous administration of morphine by lumbar epidural route for relieving postoperative pain in major surgery of the abdomen and orthopedic surgery. Lumbar epidural catheters were placed to 25 patients (mean age, 52 years) before induction of general anesthesia. All patients received a 4 mg bolus dose of morphine sulfate 1 hour before finalization of general anesthesia and subsequently they were placed on a continuous infusion of morphine sulfate at 0.3-1 mg/h. All patients achieved analgesia which maintained then pain-free and allowed early ambulation and initiation of active respiratory physiotherapy. Duration of continuous analgesia varied from 3 to 5 days. No patient presented respiratory depression; four presented nausea and eight had urinary retention. We believe that continuous epidural infusion of morphine is efficacious and safe for the treatment of acute postoperative pain in patients undergoing abdomen major surgery and orthopedic surgery.