This randomized trial investigated whether a 2-dose administration of intravenous ramosetron (5-hydroxytryptamine type 3 receptor antagonist) is more effective than a single-dose administration in preventing postoperative nausea and vomiting (PONV) in 89 patients who were scheduled to undergo laparoscopic operation for benign gynecologic diseases and to receive intravenous patient-controlled analgesia for relief of postoperative pain. After assignment at a ratio of 1:1, intravenous ramosetron (0.3 mg) was initially administered at the end of skin closure in all patients. Thereafter, ramosetron (0.3 mg) and placebo were administered to the study and control groups, respectively, at 4 hours after the operation. The baseline and operative characteristics were similar between the groups. The incidence of PONV during the 24-hour period after operation which was assessed as the primary endpoint did not differ between the groups. No serious adverse events occurred in either group. A 2-dose administration of intravenous ramosetron may not be superior to a single-dose administration in preventing PONV in patients undergoing laparoscopic operation for benign gynecologic diseases.