There are many myocardial and non-myocardial conditions that cause heart failure with normal left ventricular ejection fraction (LVEF). Among them, diastolic heart failure (heart failure due to diastolic dysfunction) is the most common cause of heart failure with normal LVEF. Diastolic heart failure easily can be diagnosed by comprehensive two-dimensional and Doppler echocardiography, which can demonstrate abnormal myocardial relaxation, decreased compliance, and increased filling pressure in the setting of normal LV dimensions and preserved LVEF. Therefore, diastolic heart failure should always be considered when LVEF is normal on two-dimensional echocardiography in patients with clinical evidence of heart failure. The diagnosis can be confirmed if Doppler echocardiography and myocardial tissue imaging provide evidence for impaired myocardial relaxation (i.e., decreased longitudinal velocity of the mitral annulus during early diastole and decreased propagation velocity mitral inflow), decreased compliance (shortened mitral A-wave duration and mitral deceleration time), and increased filling pressure (shortened isovolumic relaxation time and an increased ratio between early diastolic mitral and mitral annular velocities). Early identification of diastolic dysfunction in asymptomatic patients by the use of echocardiography may provide an opportunity to manage the underlying etiology to prevent progression to diastolic heart failure.