In this thesis associations between biological risk factors and the occurrence of coronary heart disease in elderly persons are described. The focus is on classical (i.e. total and high density lipoprotein cholesterol and blood pressure) and some new (i.e. homocysteine, white blood cell count and serum albumin) biological risk factors. The studies are based on two Dutch cohorts. One is a cohort of 292 men and women, aged 64 to 87 years in 1971, from a general practice in Rotterdam, with a mortality follow-up of 17 years. The other is the Dutch cohort of the Seven Countries Study which consists of 939 men aged 64 to 84 years in 1985 from the town of Zutphen. The morbidity and mortality follow- up embraced five years.In general, the classical risk factors were important predictors of coronary heart disease occurrence in elderly people. Systolic blood pressure was a strong independent long-term predictor of coronary heart disease mortality in elderly women, but the long-term association was less clear in elderly men. Total cholesterol was also significantly associated with long-term mortality from coronary heart disease in elderly women, but in men the association tended to be inverted U -shaped, i.e. men with cholesterol levels in the median tertile of the cholesterol distribution had a higher risk than those with levels in the first and third tertile. Regarding the Zutphen study, the short-term associations with incidence of coronary heart disease were usually weaker than with mortality from the disease. Elevated systolic and diastolic blood pressure, and especially isolated systolic hypertension, were important short-term predictors of sudden cardiac death in elderly men. For mortality from coronary heart disease, which was not additionally recorded as sudden, U -shaped associations with systolic and diastolic blood pressure levels were observed, i.e. men with the lowest blood pressure levels and those with the highest blood pressure levels and using antihypertensive medication had the highest risk. Serum total ...