The work of the ventricle alternates systolic ejection with diastolic filling, which are closely linked to each other. Diastolic dysfunction can occur with normal or abnormal ejection fraction and in the presence or absence of heart failure. In this chapter pathophysiology, causes and diagnosis (chest X-ray and ECG) of diastolic heart failure are discussed in detail. Diastolic heart failure can be associated with symptoms of dyspnea, orthopnea and paroxysmal nocturnal dyspnea. Echocardiography (ECG) is the most common and widely used imaging method to evaluate diastolic function with focus of interest mainly on left ventricle (LV) and to a lesser extent on right ventricle. New areas in clinical practice are being investigated for diastolic dysfunction to decrease patient morbidity and mortality, while newer imaging techniques are being explored for more accurate diagnosis.