In an attempt to find out the effect of epidural administration with morphine on postoperative pain relief, a small dose of morphine with a local anesthetic(lidocaine) was administered into the epidural space, either by lumbar or caudal approach. Morphine injected into the epidural space has been suggested to produce it's effect by direct action on the specific oplate receptor in the substantia gelatinosa of the posterior horn of the spinal cord. 90 patients who were anesthetized under epidural block in the Pusan Paik's Hospital, INJE Medical College, from May 1980 trhough Jan. 1981 were divided into the groups "Lidocaine alone" and "Lidocaine + Morphine". The number of patients of patients of the lumbar approach was 73 (81.1%) and of the caudal approach was 17(18.9%). The group "Lidocaine alone" numbered 45 cases which were injected with 2% lidocaine into the epidural space as an anesthetic. Group "Lidocaine + Morphine" also numbered 45 cases and received 2mg of morphine with 500 mg of 2% lidocaine as an epidural anesthetic. 0.2mg of 0.1% epinephrine was mixed to the anesthetic solution in all the above cases. The results of this study are as follows: 1) Alteration of arterial blood pressure during anesthesia was minimal within 30 minutes after injection of the epidural anesthetic in both groups. 2) Duration of postoperative pain relief in the group "Lidocaine + Morphine" was significantly extended comparing it to that in the group "Lidocaine alone". 3) Between the two groups, no significant difference was noted in recovery of spontaneous volding. 4) Complications were similar in both groups except for nausea and vomiting which occurred more frequently in the group "Lidocaine + Morphine"(8.9% and 6.7%, respectively) than in the group "Lidocaine alone" (2.2% and none, respectively). Any signs of CNS depression or neurologic sequelae were not observed.