The results of all the transesophageal echocardiographies (TEE) performed between June 1989 and February 1992 are analyzed. Five hundred patients (240 male) with a median age of 57 years (range 13-88) were examined; during the same period, 5180 transthoracic echocardiographies were performed. TEE were requested for the following reasons: valvular prosthesis disfunction in 132 patients, rheumatic valvulopathy in 103, search for embolic origins in 97, study of congenital cardiopathies in 48, bacterial endocarditis in 35, aortic dissection in 25 and miscellaneous in 78. Among congenital cardiopathies there were 29 cases of interauricular communication and among miscellaneous cases, 9 patients with cardiac tumors. No major complications occurred. The imaging quality of this technique renders it specially important in the study of prosthesis disfunction, mitral valve analysis before valvuloplasty, detection of cardiac origins of emboli and infective endocarditis complications and anatomical and dynamic analysis of aortic dissection. It is concluded that TEE is a safe technique that provides high quality images and visualizes segments of the heart and great vessels formerly inaccessible with transthoracic echocardiography. It has enlarged the diagnostic capacity of echocardiography and improved the support of therapeutic decisions.