Coronary heart disease is the leading cause of death in both men and women 65 years of age and older, and in 1982, it was estimated that it accounted for about 32.4 percent of all deaths in this age group and may have contributed to death in an additional 12.1 percent. Coronary heart disease mortality rates increase steeply with age, even in those over 65 years of age. Death rates for males continue to be higher than females although the sex ratio declined sharply with age. Data from Framingham suggest that although the incidence of coronary heart disease rises with age in both males and females, the incidence rate rises more steeply in elderly females compared with elderly males. Despite the magnitude of this problem, in 1988 the majority of the knowledge on coronary heart disease and its risk factors related to the disease in middle-aged persons--primarily males. More information was needed about coronary heart disease and its risk factors in elderly women. Also, the atherosclerotic process develops over many years and the risk factors which relate to the evolution of atherosclerosis are highly correlated within an individual. Therefore, it is likely that risk factors, such as lipoproteins and apoproteins will be important determinants of coronary heart disease in older persons primarily because of this observed correlation within individuals over time, and their long-term association with the development and progression of atherosclerosis. In addition, identification of the high risk individual is a goal of many epidemiologic investigations. It is possible that qualitative examination of the polymorphisms of the apoproteins could in fact assist in the identification of women at high risk of coronary heart disease who are in need of aggressive prophylaxis. These genetic markers represent a second generation of risk factors for coronary heart disease.