Purpose: The purpose of this study was to compare the effects of ondansetron combined with dexamethasone on Post-Operative Nausea and Vomiting (PONV) and pain with ondansetron alone in patients with laparoscopy assisted vaginal hysterectomy under general anesthesia. Methods: Data were collected from April 1 through September 30, 2005 using a double blind method. Ondansetron 4 mg and dexamethasone 10 mg were administered to the experimental group (25 patients), and ondansetron 4 mg only to the control group (25 patients). The medications were administered through an intravenous line at the beginning peritoneum suture. PONV by Index of Nausea Vomiting and Retching (INVR), nausea by Visual Analogue Scale (VAS), and pain (VAS) were assessed at postoperative 1 hr, 3 hr, 6 hr, 24 hr, and 48 hr. Data were analyzed using repeated measures ANOVA, and Bonferroni methods. Results: The experimental group that received ondansetron combined with dexamethasone had less PONV (p=.048), and nausea (p=.012) than control group that received ondansetron alone. However, there was no difference in pain (p=.557) between the patients in the two groups. Conclusion: We conclude that the administration of ondansetron combined with dexamethasone is more effective than the administration of ondansetron alone to reduce PONV in patients with laparoscopic hysterectomy.