Patients who had at least two risk factors of PONV (Postoperative nausea and vomiting) and underwent laparoscopic surgeries under general anesthesia were assessed for eligibility. Patients who developed PONV within the first 2 hours after anesthesia received intravenously, in a randomized double-blind manner, ondansetron 4 mg or ramosetron 0.3 mg. Patients were then observed for 24 hours after drug administration. The incidence of nausea and vomiting, severity of nausea, requirements for rescue antiemetic and adverse effects at 0-2 and 2-24 hours after drug administration were evaluated. The primary endpoint was the rate of patients exhibiting complete response, defined as no emesis and no further rescue antiemetic medication for 24 hours after drug administration.

Inclusion Criteria:

• age 19-65 years
• patients undergoing elective laparoscopic surgery under inhalational anesthesia
• duration of surgery between 30 min to 4 h
• ASA (American Society of Anesthesiologists) physical status I or II, and patients who had at least two of these risk factors
• female gender, history of motion sickness (MS) or PONV, nonsmoking, and the use of postoperative opioids.

Exclusion Criteria:

• patients with history of being allergic to 5-HT3 receptor antagonist
• patients with history of anticancer chemotherapy
• chronic opioids use, alcohol abuse, or drug abuse
• patients who took antiemetic medication within 24 h before surgery, steroids within 24 h before surgery or 24 h after surgery
• presence of renal (serum Cr > 1.6 mg/dl)
• hepatic(liver enzymes more than 2 times normal value) insufficiency
• patients converted to open laparotomy
• patient who are pregnant or breast-feeding
• patient with borderline QTc(corrected QT interval) prolongation (> 430 ms for male, >450 ms for female)
• patient not able to understand the scoring of pain or express the degree of PONV.