M mode echocardiography may be difficult or even impossible from the standard transducer positions (parasternal or subcostal) in obese, broncho-emphysematous patients and subjects with thoracic malformations. For this reason, the authors used the oesophageal route. A 2.25 MHz unfocused 11 mm diameter transducer was attached to a wire enabling it to be orientated. The patients were asked to swallow this probe after local anaesthesia. The aortic ring served as a landmark for other cardiac structures. The technique was well tolerated and no complications ensued. Fifty seven patients were examined: echocardiography from the standard positions was of mediocre quality in 55%. Excellent recordings were obtained by the oesophageal route, of the aortic ring (Ao, 100% of cases), of the aortic cusp opening (ACO, 92% of cases) and of the anterior mitral leaflet (AML, 96.5% of cases); the recording of the left ventricle was more difficult (LV, 45.5% of cases). Exceptionally good recording were obtained of the right heart. Correlations between the measurements made from the oesophageal and standard positions were excellent with respect to the aortic structures (Ao: r = 0.92; ACO: r = 0.92) and LV dimensions (systolic: r = 0.82; diastolic: r = 0.87). The correlations between the measurements of DE mitral valve amplitude, EF slope and left atrial dimension were mediocre (r = 0.63, r = 0.72 and r = 0.69, respectively). In 6 cases, this recording technique enabled a precise diagnosis to be made. Oesophageal echocardiography is simple and well tolerated and should effectively complete the arsenal of cardiological ultrasonic techniques.