To assess left ventricular (LV) functional and structural changes associated with the reduction of blood pressure (BP) values during nicardipine administration (60 mg daily, for two months), 17 hypertensive patients were studied by M-mode echocardiography, according to a double-blind design (11 with nicardipine and six with placebo). Decrease in BP induced by nicardipine was associated with decrease in myocardial afterload (end-systolic stress) (P less than .002) and improvement of systolic function (fractional shortening) (P less than .02), without changes in inotropic state (assessed by systolic BP/end-systolic dimension/posterior wall thickness ratio). At the end of trial, a 5% reduction was found in LV mass (P less than .002), whereas relative wall thickness did not change. Diastolic phase (assessed by relaxation time index, and the slope of EF tract of the anterior mitral valve leaflet) was improved (.01 less than P less than .001). Patients with concentric and eccentric hypertrophy were separately considered. Relaxation time index and fractional shortening were significantly improved only in patients with concentric hypertrophy (P less than .01), whereas in the other ones the effect of treatment was variable. These differences were probably due to different effects on preload in the two LV hemodynamic patterns. Thus, nicardipine shows powerful effects on cardiac mechanics in systemic hypertension, but these effects are different according to LV anatomic pattern. Only in the presence of concentric hypertrophy is it possible to foresee the improvement of LV function; LV hypertrophy can be also reduced in concentric hypertrophy, but in the short term the reduction is too small to assume pathophysiologic significance.