BACKGROUND The presence of diastolic dysfunction in a hypertensive patient is not necessarily associated to the existence of left ventricular hypertrophy. The aim of this study was to determine whether the reduction of the left ventricular mass in hypertensive patients treated with captopril is accompanied by an improvement of the diastolic filling indexes. METHODS Nineteen patients with essential hypertension were studied before and after one year of treatment with captopril. Different morphological indexes and diastolic function of the left ventricle were evaluated by mode M and Doppler echography. RESULTS The indexes of left ventricular mass diminished significantly with treatment with captopril. The thickness of the ventricular walls diminished with treatment although not significantly. No significant modification was observed in the indexes of diastolic function (quotient of speed of protodiastolic filling/speed of telediastolic filling and time of deceleration of transmitral fluid during diastole) following the treatment period. CONCLUSIONS Diminution of the left ventricular mass induced by captopril in hypertensive patients is not accompanied by an improvement in ventricular filling. It is suggested that myocardial hypertrophy is not responsible for diastolic dysfunction of arterial hypertension.