It is now clear that diastolic heart failure (DHF) is an important, perhaps even dominant form of heart failure in older Americans. However, our knowledge base regarding the epidemiology, pathophysiology, natural history, and therapy of this relatively recently recognized disorder is limited. A number of normal age related changes in the heart and vascular system may predispose to or lower the threshold for expression of DHF. Recent reports from large population-based observational studies indicate that over 50% of persons 65 years and older who have heart failure have normal LV systolic function (presumed DHF). Among these, 45% have no other confounding variables (coronary, valvular, or pulmonary disease) and meet the criteria for isolated DHF. DHF is substantially more common in older women than men. A history of systemic hypertension and left ventricular hypertrophy are almost invariably present. Mortality rates are about 50% lower in DHF than in systolic heart failure (SHF) when stable outpatients are considered. However, in hospitalized and very elderly patients, the mortality rate appears similar in DHF and SHF. Furthermore, due to its higher prevalence, the total mortality in the older population attributable to DHF exceeds that of SHF. Morbidity in DHF is substantial and approaches that of SHF. In the chronic setting, DHF patients can have severe exercise intolerance related to failure of the Frank-Starling mechanism with reduced peak cardiac output, heart rate, and stroke volume and increased LV filling pressure. DHF patients also appear to have increased vascular stiffness, accelerated systolic blood pressure response to exercise, neuroendocrine activation, and reduced quality of life. Acute exacerbations (pulmonary edema) frequently occur and are associated with severe hypertension, sodium indiscretion, and medication non-compliance. Surprisingly, overt myocardial ischemia appears to infrequently play a role in these acute exacerbations. Therapy is currently empiric and multicenter, randomized, controlled trials are urgently needed. Anecdotally, control of blood pressure appears to improve symptoms and reduce the frequency of acute exacerbations. In addition, non-pharmacologic intervention, including multi-disciplinary case management is useful.