Approximately 15 to 40% of cerebral infarctions and transient ischemic attacks (TIA) are of cardiac origin. Knowledge of a significant cardiac disease arouses the suspicion of cardiogenic embolism, but its diagnosis requires identification of the source of embolism. Atrial fibrillation is the most common cause of cardiogenic embolism, and should be actively sought after an ischemic cerebrovascular attact. The detection of atrial fibrillation or an intracardiac thrombus in these patients requires initiation of permanent anticoagulant therapy. Transesophageal echocardiography (TEE) has proven to be more sensitive than transthoracic echocardiography (TTE) in detecting certain possible cardiogenic sources of embolism.