Diastolic wall stress and compliance were determined in 74 patients with essential hypertension during diagnostic cardiac catheterization. Ventricular compliance was normal in compensated essential hypertension without coronary artery disease even at severe left ventricular hypertrophy. In contrast, additional coronary stenosis and ventricular dilatation due to cardiac decompensation was asscociated with considerable decrease in ventricular compliance. Thus, left ventricular hypertrophy in essential hypertension does not imply per se a change in ventricular compliance. A decrease in ventricular compliance was followed by a decrease of forward pump function of the left ventricle. whereas ventricular work index (as estimated as the product out of systolic wall stress and the stroke volume) increased. This disproportion between external and internal ventricular work increased with increasing ventricular dilatation and was greatest in decompensated essential hypertension. Accordingly, decompensated essential hypertension had largest ventricular work load and lowest forward pump function in comparison to all other patient groups with essential hypertension. The mass to volume ratio may be considered an important determinant of the degree of left ventricular hypertrophy in essential hypertension. The relationship between the mass to volume ratio and the systolic wall stress may provide a diagnostic and prognostic evaluation of the left ventricle in essential hypertension on the basis of dynamic ventricular geometry.