In a prospective, randomized, double blinded, placebo-controlled trial, we evaluated the efficacy of oral ramosetron 0.1 mg and metoclopramide 10 mg for the prevention of postoperative nausea and vomiting (PONV) in patients considered high risk for PONB after various types of surgery. One hundred and eighty patients ASA physical status I or II, aged 18-65 years who had at least 3 of 4 predictors of PONV (female gender, history of motion sickness or PONV, nonsmoking, and opioid use) were randomized to receive ramosetron 0.1 mg or metoclopramide 10 mg or placebo orally 1 h before the procedure. Standard general anesthetic technique and postoperative analgesia were employed. Significantly fewer patients who had received ramosetron experienced vomiting during the first 24 h compared with placebo (10% with ramosetron and 35% with placebo, P = 0.002, BB/t = 4) and fewer patients in ramosetron group required rescue antiemetice (20% with ramosetron and 43.3% with placebo, P = 0.010). There were no differences between metoclopramide and placebo. A complete response, defined as no nausea and no vomiting occurred in 60%, 25% and 41.7% in ramosetron, metoclopramide and placebo group respectively, there were no significant differences between ramosetron or metoclopramide compared with placebo. Patients who received ramosetron reported higher level of satisfaction in PONV management and overall anesthesia service (P < 0.001 and P = 0.002 respectively. We conclude that prophylactic oral ramosetron 0.1 mg effectively reduces the incidence of postoperative vomiting and the need for rescue antiemetics in patients considered high risk for PONV and associates with a significantly more satisfaction.