At the Centre of Thoracic Surgery we have so far performed 235 exams of transesophageal echocardiography (TEE). The aim of our study was critical analysis of the exams and if possible the comparison of the information given by TEE, transthoracic echocardiography (TTE) and surgery. We used biplane 5 MHz probe. The indications of the exams were: prosthetic mitral valve (58), peripheral embolization (40), clinical suspicion of infective endocarditis (32), aortic dissection (20), atrial septal defects (17), quantification of mitral insufficiency in native valve (15) and others. TEE showed prosthetic disfunction in 20 patients, spontaneous echo contrast in 17 of 40 patients and vegetations in 14. TTE identified 4 false atrial defects. TEE maintained mitral regurgitation quantification in 4 patients and changed in 9. So, TEE is important to detect most cardiac diseases.