A prospective study was made of the morbidity and mortality from ischemic heart disease in 390 patients with focal TIA caused by atherosclerotic vascular disease. The 5-year cumulative rate of myocardial infarction or sudden death in these patients was 21.0%, a rate only slightly less than that of fatal or nonfatal cerebral infarction (22.7%). Risk factors including diabetes, angina, and ECG abnormalities were associated with an increase in morbidity and mortality from ischemic heart disease. A major factor associated with these cardiac events was the presence of atherosclerotic obstructive or ulcerative lesions in the carotid arteries. These observations indicate that focal TIA caused by carotid atherosclerosis is a predictor not only of cerebral infarction, but also of serious cardiac disease and death.