Although physiologists have recognised for many years that cardiac performance is based on two functions, systolic and diastolic, it has only been in the last 15 years that clinicians have acknowledged the essentiel role of diastole in the physiopathology of cardiac disease. Many studies have shown that left ventricular diastolic dysfunction resulting from abnormal active relaxation or changes in passive visco-elastic properties of the myocardium modulating its rigidity were responsible for decreased distensibility of the ventricle and an increase in its filling pressures. Therefore, the symptoms of the majority of patients with cardiomyopathy are due, more or less, to diastolic dysfunction. This is particularly the case in hypertrophic cardiomyopathy, most case of which have diastolic dysfunction secondary to an often asymetric distribution of the hypertrophy, to the disorganisation of the myocardiofibres and to interstitial fibrosis. With respect to advanced forms of restrictive cardiomyopathy, as their clinical and haemodynamic characteristics resembling constrictive pericarditis show, they demonstrate caricatural diastolic dysfunction. Finally, although the main abnormality in dilated cardiomyopathies is poor contractility, a decrease in ventricular compliance is constantly observed.