The relationships between left ventricular mass (LVM), assessed by echocardiography, and several biohumoral and hemodynamic parameters were studied in 63 mild or moderate hypertensive patients and in an age-matched group of 23 normotensive subjects. In hypertensive patients, but not in normotensives, LVM index was significantly correlated with beta-adrenoceptor responsiveness, as evaluated by the chronotropic response to isoproterenol (CD<sub>25</sub>) (r = 0.525, p < 0.001) and with the 24-hour catecholamine urinary output (r = 0.485, p < 0.001). Both CD<sub>25</sub> and the catecholamine urinary output were significantly higher in the hypertensives as compared with the normotensive subjects. Moreover, left ventricular wall thickness (septum + posterior wall) was significantly correlated with CD<sub>25</sub> and urinary catecholamines only in hypertensive patients. No significant correlation was found between LVM or wall thickness and body surface area, age, blood pressure, heart rate, cardiac output, total peripheral resistance and left ventricular systolic wall stress, whereas CD<sub>25</sub> was correlated with urinary catecholamines only in hypertensive patients (r = 0.606, p < 0.001). These results seem to support the hypothesis that an elevated adrenergic tone may exert a permissive role in the development of left ventricular hypertrophy in human hypertension.