The two-dimensional echocardiographic and clinical features of 60 patients with echocardiographic appearance of left ventricular thrombus are described. Thrombus appeared as intracavitary echoes contiguous with the ventricular wall, most often apical in location and denser than adjacent myocardium. Large thrombi were more commonly seen in dilated cardiomyopathy than in coronary artery disease with segmental wall abnormalities or left ventricular aneurysm. The apical examination was most useful for visualizing thrombus. In 14 patients with pathologic or surgical confirmation, two-dimensional echocardiography was more accurate than angiography in correctly identifying thrombus.