The antiemetic effect of clebopride, a new derivative of the orthopramide group, was compared with that of placebo in 298 women undergoing elective surgery. A group of 150 patients received premedication of 1 mg/kg of meperidine, administered intramuscularly (IM), and a group of 148 patients received premedication of 10 mg of diazepam IM. All patients received 0.5 mg of atropine IM. Anesthesia was induced with thiopental and maintained with halogenated N2O/O2. In a double-blind procedure, clebopride (2 mg) or placebo was injected IM at the end of anesthesia and whenever a patient had a second episode of vomiting. Clebopride appeared to be better than placebo in the prevention of nausea (P less than or equal to 0.05) and vomiting (P less than or equal to 0.001) during the 12-hour observation period. The frequency of side effects was virtually the same in patients given clebopride and patients given placebo.