The aim of this review was to examine the relative contributions of systolic and diastolic blood pressures to the risk of cardiovascular disease on the basis of epidemiologic evidence from the Framingham Heart Study and the change in attitudes toward systolic blood pressure that occurred during the course of the study. Historic texts were evaluated in comparison with data from the Framingham Heart Study, a prospective longitudinal analysis of the relation between blood pressure and occurrence of subsequent cardiovascular morbidity and mortality rates in a fixed cohort. Historically, systolic hypertension has been considered an innocent accompaniment to arterial stiffening, occurring as a compensatory phenomenon in the elderly. Epidemiologic data show that the development of hypertension is neither inevitable nor beneficial. The data also provide evidence that systolic pressure is more important than diastolic pressure as a determinant of cardiovascular sequelae. Mild or moderate elevations of systolic blood pressure, even when unaccompanied by diastolic pressure elevations, are associated with an increased risk of cardiovascular disease. Risk is increased further by the added presence of related metabolic disturbances such as dyslipidemia, glucose intolerance, insulin resistance, cardiac hypertrophy, and obesity. Over-reliance on diastolic blood pressure in assessing the risk of hypertension can be misleading. Systolic pressure constitutes a powerful predictor of cardiovascular disease and a valuable tool when incorporated within multivariate risk formulas for estimating the conditional probability of coronary and stroke events.