Post-operative nausea and vomiting (PONV) is a complication of anaesthesia and responsible for malaise of surgical patients. Furthermore, PONV has been shown causing additive costs due to anti-emetic drugs and prolonged hospitalisation. The occurrence of PONV is multifactorial. Beside individual patients factors, opioid use and type of surgery seem to be responsible for occurrence of PONV. Especially, sinus surgery carries a high risk of PONV. Blood from the operation site entering the stomach has been discussed the potential cause for PONV in this specific patient population.