Diastolic dysfunction is characterized by an increased resistance to filling with increased diastolic filling pressures. A variety of disorders are associated with diastolic dysfunction, such as hypertrophy, structural alterations of the myocardium with increased fibrosis, myocardial scarring, or infiltrative processes. In addition to these changes, physiological abnormalities of the left ventricle with impaired relaxation, decreased diastolic filling, and increased stiffness of the myocardium can be observed. In patients with aortic stenosis, the most common cause for diastolic dysfunction is left ventricular hypertrophy. Diastolic dysfunction is found in approximately 50% of the patients with normal systolic ejection performance and in 100% of the patients with depressed function. Diastolic function appears either to be more sensitive for detection of abnormal left ventricular function in patients with aortic stenosis or to precede systolic dysfunction or both. Treatment of diastolic dysfunction is usually achieved by aortic valve replacement with regression of left ventricular hypertrophy, but in patients with decompensated aortic stenosis, a reduction of circulating blood volume to reduce diastolic filling pressures, and thus dyspnea, is often indicated. Prognosis of patients with diastolic dysfunction is usually better than that of patients with systolic dysfunction but is clearly worse than that of normal patients.