INTRODUCTION: Patient-controlled analgesia (PCA) has become an important means for postoperative analgesia with parenteral opioid, but postoperative nausea and vomiting (PONV) remains a major problem using a PCA system. The present study was designed to assess the antiemetic effectiveness of droperidol in patients using an intravenous PCA during the first 24 hours after surgery. METHODS: For the postoperative analgesia, 80 patients underwent orthopedic surgery were randomly allocated to receive PCA with either a mixture of 3.75 mg droperidol and fentanyl 2500 microgram after initial bolus of 1.25 mg droperidol as the FD group, or a mixture of saline and fentanyl 2500 microgram as the FS group at the end of surgery. RESULTS: The incidence of PONV showed 52.5% in FS group and 15% in FD group respectively (P<0.05). The incidence of PONV was 2~3 times more in women (76% in FS group