We evaluated the effect of verapamil therapy on left ventricular hypertrophy and left ventricular diastolic function in 13 patients with mild to moderate hypertension. Left ventricular hypertrophy was determined by M-mode echocardiographic measurements of interventricular septal thickness (IVST), posterior wall thickness (PWT) and left ventricular mass index (LVMI) both before (T0) and after 3 months (T3) of verapamil therapy. Left ventricular diastolic transmitral flow was measured by pulsed Doppler indices of early (E) and atrial (A) velocity, E/A ratio, total area (Ta), A area (Aa), Aa/Ta ratio, E-pressure half-time (E-PHT). A-pressure half-time (A-PHT) and E-PHT/A-PHT ratio both before and after 3 months of verapamil therapy. No significant changes occurred in mean heart rate, systolic function or body weight. We conclude that 3 months' therapy with verapamil resulted in an improvement in left ventricular hypertrophy and left ventricular diastolic function and a normalization of blood pressure, without a corresponding deterioration in left ventricular systolic function.