Possible intracardiac sources of emboli were looked for by transoesophageal echocardiography (TOE) in 271 patients (149 men, 122 women; mean age 60 +/- 11 years) a mean of 12 +/- 8 days after suffering an episode of cerebral ischaemia. Left atrial thrombi were revealed in 9 patients: they were more frequent in those with atrial fibrillation (odds ratio [OD] 25.2; P < 0.0001) or known cardiac disease (OD 3.5; P = 0.06). Using the two factors together, the 9 left atrial thrombi could be predicted in 96 patients, while in the remaining 175 patients without cardiac abnormalities no left atrial thrombi were found. Overall, TOE is not an essential investigation additional to transthoracic echocardiography to exclude left atrial thrombi in patients without heart disease who are in sinus rhythm. But in those with atrial fibrillation and/or organic heart disease, TOE can in many instances facilitate the indication for anticoagulation.