Forty-seven patients with acute arterial embolism requiring urgent embolectomy had postoperative echocardiography (36 2-D, 11 M-mode) in an attempt to identify a cardiac source of emboli. On the basis of history, physical examination, electrocardiogram, and chest roentgenogram, 37 patients were believed to have an apparent cardiac source. All histories and physical examinations in this group reaffirmed significant underlying cardiac disease. Nine of the 47 patients had no discernible source based on clinical data, and one had an arterioarterial embolus. In the presence of a clinically obvious source, although echocardiography (26 2-D, 11 M-mode) helped to clearly define evident cardiac disease in these patients, it failed to demonstrate a cardiac embolic source in those without clinical evidence of cardiac disease or to influence subsequent management. The continued use of echocardiography for the sole purpose of identifying a potential cardiac embolic source should be reconsidered.