BACKGROUND: Postoperative nausea and vomiting (PONV) is a distressing adverse effect of anesthesia. This study was designed to evaluate antiemetic effects of metoclopramide, ondansetron and granisetron in middle ear surgery. METHODS: We compared the antiemetic activity of prophylactic administration of metoclopramide, ondansetron and granisetron in 103 patients undergoing middle ear surgery (tympanomastoidectomy and tympanoplasty). All Study drugs were given as a short intravenous infusion 30 minutes before the end of anesthesia. The incidence of PONV were assessed by direct questioning of patients at 6, 12, 24 and 48 hr after recovery from anesthesia. RESULTS: For the first 6 hr recovery period after surgery, the percentages of emesis in patients were 46.7%, 16%, 12% and 16% in the control, metoclopramide, ondansetron and granisetron groups respectively. After 6 hr, the percentage of emesis in patients significantly decreased in the control, ondansetron and granisetron groups when compared with the first 6 hr, but in the metoclopramide group there was no changes after 6 hr. CONCLUSIONS: The antiemetic drugs, metoclopramide, ondansetron and granisetron, were all effective in controling PONV in middle ear surgery.