The epidemiologic investigation of heart failure evolution by the Framingham Heart Study has provided vital clues concerning the pathogenesis, predisposing conditions, other predictive risk factors, and indicators of deteriorating ventricular function related to the disease. This information is important in the early detection of those susceptible to heart failure who are candidates for preventive measures-of importance because the prevalence of the disease has not declined despite the recent therapeutic advances. Epidemiologic investigation has identified useful indicators for the disease including a low or falling vital capacity suggesting diastolic dysfunction, a rapid resting heart rate in compensation for a decreased stroke volume, and cardiomegaly indicating myocardial hypertrophy or dilatation. Hypertension and coronary disease remain the leading causes of the disease, and heart failure due to myocardial infarction has increased in prevalence. Hypertension and coronary disease often coexist in individuals who develop heart failure so that correction and prevention of these conditions deserve a high priority. Early detection and correction of insulin resistance is important because a threefold increase in the prevalence of diabetes in the general population has serious implications for the incidence of heart failure. In patients with hypertension, the occurrence of a myocardial infarction increases the risk of developing heart failure five to sixfold, whereas angina increases it less than twofold. In these patients, the presence of left ventricular hypertrophy increases the risk of developing heart failure two- to threefold. Heart failure-related mortality remains unacceptably high, despite improvements in treatment, indicating a need for early detection and treatment of predisposing conditions.