Post-operative nausea and vomiting (PONV) is one of the most frequent and distressing complications of anesthesia. Patients often rate that PONV is worse than postoperative pain. PONV alone is one of the leading causes for delayed discharge and unpleasant experiments. Although PONV is not always life-threatening, persistent cases can result in dehydration, esophageal rupture, aspiration and potential death. The massive ingested blood and the additional issue of an altered diet (full liquids) due to a short period of jaw immobilization may be associated with a higher prevalence of PONV after orthognathic surgeries.