BACKGROUND: Epidural opioids are used for the treatment of postoperative pain, but the incidence of side effects like nausea, vomiting, and pruritus is high. The aim of this study was to determine the optimal method for administering epidural droperidol to reduce the side effects of epidural opioids. METHODS: A randomly sampled group of 145 patients that had undergone abdominal or lower leg surgery under general anesthesia were divided into the four groups. All patients received morphine 4 mg, fentanyl 500microgram and 0.2% ropivacaine 100 ml using a 2-day epidural infusion pump, and morphine 1 mg, fentanyl 50 mg and 0.2% ropivacaine 10 ml by epidural bolus. Group 1 patients (control group, n = 40) did not receive epidural droperidol. Group 2 patients (n = 35) received 2.5 mg of droperidol as an epidural bolus. Group 3 patients (n = 35) received 2.5 mg of droperidol as a continuous infusion. Group 4 patients (n = 35) received 1.25 mg of droperidol as an epidural bolus and 1.25 mg of droperidol as a continuous infusion simultaneously. Nausea, vomiting, and pruritus were assessed and recorded by a blind observer 1, 6, 24, and 48 hours after the bolus epidural administration of droperidol. RESULTS: There was no significant difference between the four groups in terms of the intensity of sedation, nausea, vomiting, and pruritus. The incidence of nausea and vomiting in groups 2, 3, and 4 at 1 hour, in groups 2 and 4 at 6 hours, and in groups 3 at 48 hours was significantly lower than in control group. The incidences of pruritus in groups 2, 3, and 4 at 6 hours, and in groups 3 and 4 at 24 and 48 hours were significantly less than that of the control group. CONCLUSIONS: Epidural bolus droperidol is effective at reducing nausea, and vomiting during the early postoperative stage. Continuous epidural droperidol is also effective at reducing the pruritus during the late postoperative stage.