The aim of the study was to analyze the relationship between the magnitude of left ventricular (LV) hypertrophy and selected haemodynamic parameters reflecting LV systolic and diastolic function. The "hypertrophy-function" relationship was evaluated in 22 patients with dilated cardiomyopathy (DCM) and in patients with left ventricular dilatation resulting from volume overload due to valve disease (DVOL). The parametres of systolic and diastolic left ventricular function were obtained from right- and left-heart catheterization and quantitative angiocardiography, DCM patients were divided into subgroups depending on the magnitude of hypertrophy and degree of dilatation: Ia- moderate hypertrophy (100 g/m2 < LVMI < 175 g/m2). Ib- massive hypertrophy (LVMI > 175 g/m2); IIa- mass/volume ratio (M/V) < 1.1, and IIb - M/V > 1.1. It was found that the magnitude of myocardial hypertrophy and the M/V ratio do not affect the degree of systolic and diastolic dysfunction in patients with DCM. Myocardial hypertrophy accompanying dilatation due to DCM and DVOL showed very similar progression of impairment of isovolumetric systole and relaxation. Significant differences in EF, LVMDP and LVEDP may result from a different degree of total LV volume stiffness as a consequence of various mechanisms of hypertrophy in DCM and DVOL.