Usefulness of computerized mechanocardiography and echocardiography in the diagnosis of impaired left ventricular diastolic function is shown in a study comparing 17 hypertrophic obstructive cardiomyopathy and 17 hypertensive cardiomyopathy patients to 20 normal subjects. Mechanocardiography allows the evaluation of three different parameters of diastolic function: isovolumic relaxation evaluated by S2a-O or better by t-dr/dt and dr/dt/A2 ratio, left ventricular compliance by the A/H ratio and time of rapid filling. All the parameters are impaired in both pathological populations. Isovolumic relaxation being more depressed in hypertensive cardiomyopathy and duration of rapid filling being prolonged especially in the hypertrophic obstructive cardiomyopathy patients. Although the differences are small indicating only trends computerized mechanocardiography gives some evidence for difference in the alteration of diastolic function in hypertrophic obstructive cardiomyopathy and hypertensive cardiomyopathy.