OBJECTIVE: To study the efficacy of ginger in prevention of nausea and vomiting after major gynecologic surgery. STUDY DESIGN: Double blind randomized controlled trial. SETTING: Department of Obstetrics and Gynecology, Thammasat University Hospital, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand. MATERIAL AND METHOD: From March 2005 to April 2006, 120 patients who underwent major gynecologic surgery were randomized into group A (n = 60) and group B (n = 60). The patients in group A received two capsules of ginger taken one hour before the procedure (one capsule contains 0.5 gram of ginger powder). The patients in group B received the placebo. The visual analog nausea score (VANS) and frequency of vomiting were evaluated at 0, 2, 6, 12, and 24 hours after the operation. RESULTS: The results demonstrated the statistically significant differences in nausea between group A (48.3%) and group B (66.7%). The VANS was lower in group A compared to group B at 2, 6, 12, and 24 hours. The most statistically significant differences occurred at 2 and 6 hour. The incidence and frequency of vomiting in group A were lower than group B. Side effects caused by ginger were not detected. CONCLUSION: Ginger has efficacy in prevention of nausea and vomiting after major gynecologic surgery.