One-sixth of all cerebral infarctions are the result of cardioembolic phenomena. The certainty with which the diagnosis of cardioembolic stroke is made, however, is frequently questioned. This has partly been the result of the low sensitivity of traditional cardiac diagnostic procedures, such as surface transthoracic echocardiography and Holter monitoring. Transesophageal echocardiography is a relatively new technique that has been shown to increase the yield for demonstrating cardiac abnormalities capable of producing brain embolism, particularly disease of the left atrium, left atrial appendage, and atrial septum. The sensitivity of this technique for documenting intracardiac thrombi, mitral valve prolapse, left atrial spontaneous contrast, particularly in comparison with transthoracic echocardiography is examined after reviewing the published series.