OBJECTIVE To compare haloperidol to droperidol, both with dexamethasone, for antiemetic prophylaxis in elective laparoscopic cholecystectomy. METHODS Prospective, randomized double-blind trial enrolling 75 ASA 1-2 patients who received anesthesia with propofol and remifentanil. After induction, 8 mg of intravenous dexamethasone was administered. After surgery, depending on group assignment, patients received 10 microg x kg(-1) of intravenous haloperidol (n = 25), 10 microg x kg(-1) of droperidol (n = 25), or physiologic saline solution (n = 25). Outcomes recorded were episodes of nausea or vomiting in the postoperative period (first 6 hours and/or 6-24 hours), requirement for antiemetic agents, morphine consumption, pain assessed on a visual analog scale, level of sedation, and adverse effects. RESULTS Five patients in the haloperidol group, 6 in the droperidol group, and 13 in the control group experienced an episode of nausea or vomiting in the 24-hour postoperative period (P < .05 between the active treatment groups and the control group). One patient in the haloperidol group, 6 in the droperidol group, and 8 in the control group reported nausea in the first 6 hours (P < .05). Three patients in the haloperidol group, 1 in the droperidol group, and 8 in the control group reported nausea in the later postoperative period (6-24 hours) (P < .05, droperidol vs control). Three patients in the haloperidol group, 1 in the droperidol group, and 7 in the control group experienced late vomiting (P < .05, droperidol vs control). CONCLUSIONS Either haloperidol or droperidol in combination with dexamethasone is more effective than dexamethasone alone for antiemetic prophylaxis after laparoscopic cholecystectomy.