Opioid-related side effects, including nausea and vomiting, are common in patients using morphine in patient-controlled analgesia for postoperative pain relief. The purpose of this study was to determine if the addition of droperidol to a morphine sulfate delivery system could decrease the incidences of nausea and vomiting without increasing droperidol-related side effects. Forty ASA 1 and 2 patients scheduled to undergo peripheral orthopedic surgery were randomized to receive either morphine sulfate (2 mg/mL), or morphine sulfate (1.9 mg/mL) plus droperidol (0.125 mg/mL) for postoperative self-controlled analgesia. Visual analogue scores for pain, nausea, and sedation were obtained from each patient immediately after surgery and each morning and evening until patient-controlled analgesia was discontinued approximately 48 hours later. Total patient-controlled use of morphine sulfate was recorded at each visual analogue rating. The patients who used morphine sulfate plus droperidol had significantly less nausea and vomiting and used significantly less morphine. No patient experienced droperidol-related side effects. We conclude that the routine addition of droperidol to morphine sulfate in self-controlled analgesia improves the comfort of patients following peripheral orthopedic surgery.