Coronary heart disease (CHD) and stroke are major cases of death in U.S. and all other industrialized nations. High dietary cholesterol is now well recognized as a major atherosclerotic risk factor. In addition to the quantity of cholesterol and total fat consumed, the type and source of fat also are known to be important in determining atherosclerosis risk. For example, saturated fatty acid consumption raises plasma cholesterol and atherosclerosis risk, while consumption of vegetable oils high in polyunsaturated fatty acids appear to lower them. Marine oils which are high in omega-3 fatty acids appear to be protective against CHD. To further clarify the role that various specific fatty acids play in atherosclerosis, we plan to measure by gas- liquid chromatography the relative concentrations of all saturated and unsaturated fatty acids found in the cholesterol ester and phospholipid fractions of plasma from 4,000 middle-aged subjects from the Minneapolis area who are participating in the Atherosclerosis Risk in Communities (ARIC) Study. The ARIC study is a large, milticenter, cooperative NIH funded study designed to investigate the etiology and natural history of atherosclerosis. Large amounts of clinical and laboratory data is collected along with direct visualization of the atherosclerotic process via ultrasound of the carotid and popliteal arteries. We plan to use these fatty acid data to investigate associations of plasma abundance of specific saturated, mononunsaturated, and polyunsaturated fatty acids with: 1) various physiologic parameters that are currently being measured by the ARIC study such as plasma lipids, hemostatic parameters, and blood pressure, and to look at these associations in subgroups according to age, sex, smoking status, etc., 2) ultrasonographically identified carotid artery atherosclerosis present on ARIC baseline or three year follow-up examination, 3) clinical cardiovascular endpoints of the the ARIC study, namely myocardial infarction and stroke, as these events occur in ARIC participants.