 Over the past two decades, perioperative TOE has become routine part of monitoring in the setting of cardiac surgery. In many centres around the world nearly 100 of pateints undergoing cardiac surgery are monitored using this modality. There are several studies and observational reviews suggesting intraoperative TOE can change management and thus indirectly influence outcome in patients undergoing valve, aortic or bypass graft surgery. Certainly in our centre at The Heart Hospital, it is routine practce to perform an intraoperative TOE in all patients undergoing cardiac surgery in order to guide surgical and anaesthetic management of the patient. Despite this use of TOE there is very little evidence of how TOE influences patient related outcomes, both morbidity and mortality. 