BACKGROUND: Epidural morphine is effective in the treatment of postoperative pain, but the incidence of associated side effects is high. To evaluate the reduction of opioid sideeffects by epidural use of droperidol mixture, this study was performed. METHODS: Randomly sampled sixty patients undergoing upper abdominal surgery were divided into two groups. To assess a reduction of opioid side effects by droperidol, group I (n=30) were received 3mg morphine and 0.15% bupivacaine 10ml through the indwelling epidural catheter before the conclusion of operation, followed by an infusion of 6 mg morphine plus 0.15% bupivacaine 100ml with the two day infusor. Group II (n=30) were treated with the same protocol as group I but 1.5 mg of droperidol was added to initial bolus and 5mg of droperidol to the two day infusor. Analgesic effect and side effect were 48 hours after operation. RESULTS: No significant differences in intensity of analgesiaand sedation were seen. The intensity of nausea and vomiting in the group II was significantly less than in the group I at 8, 12 hours after operation (p<0.05). The intensity of pruritus in group II was significantly less than in group I at 4, 8 hours of postoperative period (p<0.05). The frequency of nausea, vomiting, pruritus and urinary retention in group II were less than in group I. respiratory depression. Epidural injection of droperidol did not result in any local or systemic side effects. CONCLUSION: The addition of epidural droperidol significantly reduced the side effects of epidural morphine without altering the effect on analgesia.