Women (185) undergoing elective orthopedic surgery under balanced general anesthesia were given 5 or 10 mg of domperidone, 1.25 mg of droperidol, 10 mg of metoclopramide, or a saline placebo intravenously in a double-blind random fashion 5 minutes before the end of anesthesia to prevent postoperative vomiting. Administration of the same antiemetic was repeated intramuscularly during the first 24 hours postoperatively if the patient complained of nausea or retched or vomited. Sigificantly (p less than 0.05 to p less than 0.001), fewer of the patients given droperidol were nauseated (25%) or vomited (17%) in comparison with patients given saline (incidence of nausea was 55% and vomiting 40%). Incidences of nausea and vomiting were similar in patients given domperidone, metoclopramide, or saline. Furthermore, 39 to 45% of the patients given domperidone, metoclopramide, or saline needed additional doses of the same drug, whereas only 22% of the patient given droperidol required a second dose. It is concluded that droperidol is effective in the prevention and treatment of postoperative nausea and vomiting after balanced general anesthesia but that domperidone or metoclopramide are not.