Although still unclear, it is postulated that the etiology of postoperative nausea and vomiting is the central mechanism involving stimulation of the chemoreceptor trigger zone (CTZ) located bilaterally at the floor of the fourth ventricle in the area postrema. The CTZ is sensitive to toxins and other substances in the blood and cerebrospinal fluid. The CTZ also receives sensory signals from the gastro-intestinal tract. The are three major central nervous system (CNS) areas involved with PONV which all have specific emetogenic receptors. Blockade of these receptors is postulated to be the mechanism of action of the commonly used antiemetics. The agents' antagonist activity may be at one or more receptors with different binding affinities and acting at different emetic neuroreceptors. The multifactorial etiology of PONV involving multiple receptors is believed to be the reason one single agent is not 100% effective. The administration of an agent working on one receptor type will typically reduce the PONV incidence by 30%. Use of a combination of antiemetic agents acting on different receptor sites will further reduce the incidence. This combination has shown greater efficacy than a single agent alone. Although this regimen has improved outcomes it has not eliminated the problem of PONV and patients needing rescue therapy post surgery occurs frequently. It would appear reasonable to assume that the use of more than 2 antiemetics would further reduce the incidence of PONV.43 However; published evidence of greater than 2 agents is scarce. Therefore, the main objective of our proposal is to study a combination antiemetic regimen (3 agents vs. 2 agents) in females scheduled for breast surgery, a patient population considered at high risk for postoperative vomiting. The selected agents will cover different receptors based on the hypothesized PONV multifactorial etiology with stimulation of several factors. It is unknown which of these receptors may be stimulated and by which stimuli (anesthetic, surgery, or patient factors).