Background : The purpose of this study was to compare the effectiveness of ondansetron plus dexamethasone versus ondansetron alone in the prevention of postoperative nausea and vomiting for the patient using a patient controlled analgesia (PCA). Methods : Of sixty women having general anesthesia for total abdominal hysterectomy (TAH), thirty received intravenous ondansetron 4 mg plus 150 μg/kg of dexamethasone (Group 1) and thirty received intravenous ondansetron 4 mg plus saline 2 ml (Group 2) after awakening. Butorphanol 10 mg, ketorolac 180 mg and ondansetron 4 mg were connected to PCA pump for postoperative pain control. The severity of nausea, vomiting and pain were assessed at 0, 1, 2, 6, 12, 24, 36 and 48 hr after awakening. Results : Nausea and vomiting occurred in 5 patients in Group 1 and in 4 patients in Group 2. There were no significant differences between groups in nausea, vomiting and pain scores. Conclusions : The combination of ondansetron and dexamethasone is not more effective than ondansetron alone in prevention of postoperative nausea, vomiting and pain for women having PCA following TAH. (Korean J Anesthesiol 1999; 36: 469∼473)