With transthoracic echocardiography, many pathologies can certainly be seen, but in a number of cases, due to the anatomical and physiological characteristics of the patient (thick layer of subcutaneous fat, large breast size in women, lung disease, chest deformation, etc.) hearts can not be fully explored. The use of a transoesophageal sensor can overcome all these difficulties. The review highlights the methodology, indications, and possibilities of transesophageal echocardiogram in the main heart diseases (coronary heart disease, congenital and acquired heart defects, arrhythmias) and acute pathological conditions (acute dissection of the aorta, air embolism).