One hundred and fourteen normotensive subjects without family history of hypertension and coronary heart disease have been studied by two-dimensional-targeted M-mode echocardiography to determine the sexspecific range of normal values of left ventricular (LV) systolic function and anatomy. LV mass and end-diastolic dimension were analyzed by stepwise multiple linear regression analysis, using body surface area, age, systolic blood pressure, and heart rate as independent variables. The same analysis was employed to derive fractional shortening from its hemodynamic determinants. Age influenced either LV dimension and weight or systolic blood pressure and was inversely related to heart rate (p p > 0.001). The end-diastolic dimension was influenced by heart rate and body surface in both men and women; age had importance only in men. Sex differences in lean body mass, in the content of collagen in the cardiac muscle, and in genetic and hormonal influences could be involved in these findings. Afterload and LV performance were the main variables affecting systolic function. True échocardiographie values of another small group of 16 normal subjects were related to the derived ones from multiple regression equations, providing a preliminary result indicating the reliability of equations.