Postoperative pain, nausea and vomiting (PONV) are the most common complications after anesthesia and surgery. Women undergoing mastectomy with axillary dissection are at a particularly high risk for the development of PONV and an incidence of 60-80% in patients receiving no antiemetic has been reported. Emetic episodes predispose to aspiration of gastric contents, wound dehiscence, psychological distress, and delayed recovery and discharge times. These justify the use of prophylactic antiemetics in women scheduled for mastectomy. Most of the currently used antiemetics, including antihistamines, butyrophenones and dopamine receptor antagonists have been reported to cause occasional undesirable adverse effects, such as excessive sedation, hypotension, dry mouth, dysphoria, hallucinations and extrapyramidal signs. Antiserotonins (e.g., ondansetron) are available for the prevention and treatment of PONV in patients undergoing various types of surgery. However, the use of prophylactic antiemetic therapy with antiserotonins has been criticized for being too expensive.