Transoesophageal Doppler-echocardiography is a new heart imaging technique avoiding many of the problems which sometimes limit standard transthoracic exploration. The transducer, mounted on a fibroscope sheath, is introduced into the oesophagus and therefore lies in the immediate vicinity of the atrial complex, the mitral valve, the aortic valve and the different segments of the thoracic aorta. The examination can be carried out on ambulatory patients in the echocardiography laboratory. The main clinical indications of this technique are: studies of prosthetic valves (notably the mitral valve); detection of vegetations or annular abscesses in infective endocarditis; determination of an emboligenic focus after arterial embolism; study of the causative mechanism in mitral valve regurgitation; pathology of the thoracic aorta and, in particular, of aortic dissection. The usual lack of difficulty in skilled hands, the quality of the images obtained and the diagnostic value of information collected by this route explain why this relatively new technique has very rapidly progressed from evaluation to routine use in most echocardiography laboratories.