Death certificate files were used to identify early coronary deaths which were defined as before age 55 in men and before age 65 in women. Mail and phone contacts were made to the surviving offspring, spouses, or siblings of the deceased proband to determine risk factor profiles for probands and close relatives. Hospital charts were also abstracted to assess risk factor profiles for probands. Clinical screening of the relatives of coronary probands were conducted using a detailed protocol assessing all standard coronary risk factors. Fasting blood tests were obtained for total cholesterol, triglycerides, high density lipoprotein, apo B, apo A-1, and apo E. At clinical screening, information was obtained on relationships, dates and places of vital events for the index person, spouse, offspring, siblings, parents, aunts and uncles, grandparents, grand aunts and uncles, and great-grandparents. Information was obtained on blood pressure, height, weight, electrocardiograms, physician's history and physical examination. Information was also collected on tobacco and alcohol use, hospitalization, medication usage, socioeconomic status, Type A personality, physical activity, and reproductive history.