Transoesophageal echocardiography (TOE), a minimal-risk, semi-invasive imaging procedure is nowadays an indispensable part of routine echocardiography. It is mainly necessary and indicated: ◆ To analyse some structures insufficiently seen transthoracically, such as the left atrial appendage or the thoracic aorta. ◆ In situations that prohibit the use of conventional transthoracic windows, such as the patient undergoing cardiac surgery.As in transthoracic echocardiography (TTE), the TOE examination consists of a sequence of views defined by internal landmarks; unlike TTE, depending on the patient’s tolerance and the clinical question, not all of these have to be obtained in every examination. Important typical indications for TOE are the search for signs of endocarditis, the search for cardiogenic emboli, diagnosis of left atrial (appendage) thrombi before cardioversion, diagnosis of aortic dissection, characterization of mitral and aortic valve pathology especially in the context of surgical repair, intraoperative monitoring of left ventricular function, and monitoring of interventional cardiac procedures monitored.For some indications, intracardiac echocardiography has been found useful. This procedure involves insertion of a transducer-tipped catheter into the caval vein and advancement to the right heart, or intra-aortic placement. Applications are electrophysiological procedures, interventional closure of atrial septal defect, aortic stent placement, and others.