Background: Tropisetrone either alone or in combination had observed to decrease the incidence oj postoperative nausea and vomiting (PONV) by patients undergoing surgical procedures under general anesthesia. This study compared the saJety and e.fficacy oj tropisetrone 5mg. ondansetrone 4mg alone and in combination with dexamethasone. Methods: This study had a randomized, placebo-controlled design and comprised 100 non-pregnant Jemale allocated in 5 groups (20, each) undergoing laparoscopic gynecological surgery under general anesthesia. Patients had received either a single bolus oj tropisetrone 5mg (Group T), ondansetrone 4mg (Group 0), tropisetrone 5mg plus dexamethasone Bmg .. (Group T+D) , ondansetrone 4mg plus dexamethasone Bmg (Group O+D), or saline (Group C) given at induction ojanesthesia. Results: The groups were similar with respect to demographic data and potential confounding variables. With regard to the incidence of PONV, group [O+DJ and group [T+DJ were significantly superior to group T and 0, (P30.05), except 1B hours after recovery oj anesthesia, where the difference was significant, (P2