153 patients (mean age 42 years, range 16-60) who had arterial embolic events were examined prospectively by transthoracic and transoesophageal echocardiography. Patients older than 60 years and those with evidence of extracranial carotid artery occlusive disease were excluded. 84 patients had a cerebral ischaemic event, 50 patients had embolic events in an abdominal organ or limb, and 19 patients had acute retinal ischaemia. The transthoracic echocardiographic examination was normal in 92 patients (60%), whereas only 65 patients (42%) had normal findings after both transthoracic and transoesophageal examination (p less than 0.005). Intracardiac masses, including valvular vegetations, were found in 39 patients (25%), including 27% of patients with cerebral embolism and 32% of these with peripheral embolism, but in none of the patients with retinal ischaemia (p less than 0.001). 47 patients (31%) had valvular disease, 10 (7%) had wall motion abnormalities, 23 (15%) had abnormalities of the interatrial septum, and 9 patients (6%) had diseases of the thoracic aorta. Cardiovascular abnormalities were frequently found by echocardiography in patients with arterial emboli. The transesophageal technique significantly increased the chance of detecting such abnormalities, especially intracardiac masses.