Between September 1992 and August 1993 transoesophageal echocardiography was undertaken in 30 patients with clinical and scintigraphic signs of pulmonary embolism. The diagnosis was confirmed by pulmonary angiography (1 patient had failure of venous puncture; 1 patient refused the investigation). The aim of this study was to assess the tolerance and to determine the diagnostic value of transoesophageal echocardiography in patients with suspected pulmonary embolism (PE). Two groups of patients were identified: Group 1: presence of thrombus in the pulmonary artery on transoesophageal echocardiography and group 2: absence of visible thrombus. The produce was well tolerated in all patients. In 21 cases (group 1) 21 thrombi were observed in the right pulmonary artery and 4 thrombi in the left pulmonary artery. The appearances were those of a mobile venous thrombosis in 20 cases (91%) and of clearcut amputation of the proximal segment of the right pulmonary artery in 1 case. No thrombus was detected in 9 patients (group 2). In group 1, the first clinical signs occurred 12 +/- 12 days and the latest signs 2 +/- 3 days before the investigation. One patient had a history of chronic bronchitis. Two patients had a history of PE but with no sign of chronic post-embolic cor pulmonale. Twenty patients underwent pulmonary angiography. Miller's index was 71 +/- 9% and obstruction of proximal pulmonary arteries was observed in 20 patients. In group 2, the PE was confirmed at angiography in 8 cases. The first clinical signs dated from 27 +/- 54 days and the latest signs were observed 6 +/- 4 days before investigation.(ABSTRACT TRUNCATED AT 250 WORDS)