The prognostic significance of risk factors for ischemic and hypertensive heart disease in the aged differs in many respects from that in younger persons. In old age, most risk factors for ischemic heart disease such as an elevated level of total serum cholesterol, cigarette smoking, obesity, Type A personality and abnormal glucose tolerance have a less adverse effect on morbidity and mortality from ischemic heart disease, while an elevated level of high density lipoprotein, and moderation in the use of alcohol each have a favorable effect. A high level of low-density lipoprotein cholesterol exerts an adverse effect. Both systolic and diastolic hypertension have an adverse influence on morbidity and mortality from ischemic and hypertensive heart disease, as does the electrocardiogrpahic pattern of left ventricular strain. Long-term controlled studies are needed to determine the effects on mortality and morbidity of the modification of risk factors by means of drugs, diet, and change of lifestyle. Such studies are necessary if we are to determine whether hoped-for favorable changes are offset by potential side effects on physical and mental health.