BACKGROUND: Epidural pain control has been used extensively for postoperative pain management, but nausea, vomiting and pruritus associated with morphine and fentanyl administration remain intractable problems. The aim of this study is to find the optimal epidural droperidol dosage for reducing the side effects of epidural morphine and fentanyl. METHODS: 140 patients randomly sampled and undergoing vaginal total hysterectomy were divided into 7 groups. Groups I and IV, and groups II and V, and groups III and VI, received 5 mg, 3.75 mg, 2.5 mg of droperidol by 2-day infusion pump through the indwelling epidural catheter, respectively. Group IV, V, VI patients received 1.25 mg of bolus droperidol through the indwelling epidural catheter at the time of peritoneal closure. As group VII was the control group, these patients received only epidural analgesics (morphine 10 mg, fentanyl citrate 300 microgram and 0.05% bupivacaine 100 ml) by 2-day infusion pump. RESULTS: Droperidol significantly reduced the incidence and severity of postoperative nausea, vomiting and itching sensation compared with the control group but verbal rating scale (VRS) of sedation was increased with the dosage of droperidol. There was no significant difference in the intensity of analgesia between the there groups. CONCLUSIONS: An effective epidural droperidol dosage for reducing postoperative nausea, vomiting and pruritus due to epidural pain control is 2.5 mg by 2-day infusion pump.