Recent analyses of midwall left ventricular mechanics have demonstrated that patients with established hypertension and ventricular hypertrophy have depressed myocardial contractility. In this study, myocardial performance was assessed in subjects with borderline blood pressure elevations by relating the velocity of circumferential midwall fiber shortening to end-systolic stress in young men and women who were classified as normotensive (n = 92) or as having marginally elevated blood pressure (n = 43) based on daytime ambulatory systolic blood pressure. On average, velocity of midwall fiber shortening in those with higher blood pressure was 8% greater than predicted from results of normotensive controls. These results suggest that young patients with borderline blood pressure elevations have enhanced left ventricular contractility.