Diastolic heart failure, a major cause of morbidity and mortality, is defined as symptoms of heart failure in a patient with preserved left ventricular function. It is characterized by a stiff left ventricle with decreased compliance and impaired relaxation, which leads to increased end diastolic pressure. Signs and symptoms are similar to those of heart failure with systolic dysfunction. The diagnosis of diastolic heart failure is best made with Doppler echocardiography. Based on current knowledge, pharmacologic treatment of diastolic heart failure should focus on normalizing blood pressure, promoting regression of left ventricular hypertrophy, avoiding tachycardia, treating symptoms of congestion, and maintaining normal atrial contraction when possible. Diuretic therapy is the mainstay of treatment for preventing pulmonary congestion, while beta blockers appear to be useful in preventing tachycardia and thereby prolonging left ventricular diastolic filling time. Angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers may be beneficial in patients with diastolic dysfunction, especially those with hypertension. Evidence from adequately powered randomized controlled trials, however, is not available yet. The outcomes of ongoing clinical trials may provide much-needed information to move from intuitive treatment to therapy based on evidence that matters: decreased morbidity and mortality and improved quality of life. (Am Fam Physician 2004;69:2609–16. Copyright © 2004 American Academy of Family Physicians.)