Abstract--Isolated systolic hypertension is predominantly observed in the elderly because of increased arterial stiffness. Aggressive treatment leads to excessive lowering of diastolic blood pressure and favors the presence of a J-shaped curve association with mortality. We investigated whether, in the elderly, this pattern of association is a simple epiphenomenon of increased arterial stiffness and impaired cardiac function. In a cohort of 331 hospitalized subjects >70 years old (mean age±SD: 85±7 years), aortic pulse wave velocity and pressure wave reflections, by pulse wave analysis, and cardiac function, by ultrasound, were assessed. During a 2-year follow-up period, 110 subjects died. No association of prognosis with systolic pressure, pulse pressure, or pulse wave velocity was observed. A J-shaped association between diastolic pressure and overall and cardiovascular mortality was observed. Unadjusted Cox regression analysis showed that patients in the first tertile of diastolic pressure (60 mm Hg) had higher mortality. In Cox regression analysis, diastolic pressure 60 mm Hg was a predictor of mortality independently from cardiac-vascular properties, cardiovascular risk factors, and drug treatment. Multivariate regression analysis showed that increased age and low total peripheral resistance, but not left ventricular function, were the cardinal determinants of low diastolic pressure. An "optimal" diastolic pressure of 70 mm Hg in subjects with isolated systolic hypertension was found. We showed that, in the frail elderly, a value of diastolic blood pressure 60 mm Hg is associated with reduced survival, independent from large artery stiffness and left ventricular function, suggesting that more rational antihypertensive therapy, not only based on systolic pressure level, is needed.