The evaluation of patients with left ventricular hypertrophy and the clinical syndrome of congestive heart failure requires the ability to distinguish between the etiologia of abnormal systolic contractile function and abnormalities of diastolic relaxation and filling. In patients with left ventricular hypertrophy and congestive heart failure, predominant diastolic dysfunction should be suspected when elevation of left ventricular diastolic pressure is detected in the presence of normal diastolic chamber volume or dimensions and preserved systolic shortening. The mechanisms which account for diastolic dysfunction in the presence of cardiac hypertrophy are controversial and are likely to be multiple. These mechanisms may include changes in left ventricular geometry, per se, changes in the composition of the left ventricular wall (fibrosis or alteration in collagen), and dynamic factors which modulate diastolic force inactivation (loading conditions, cytosolic calcium handling, cyclic AMP availability). In addition, recent studies suggest that hypertrophied cardiac muscle may be particularly susceptible to develop diastolic dysfunction in response to the stress of hypoxia or ischaemia.