Left ventricular (LV) morphology and function (echocardiography) were assessed in a population-derived sample of young normotensive men with a positive (PFH, n = 15) or negative (NFH, n = 29) family history of hypertension for at least two generations. Since subjects with PFH were overweight (mean weight, 89 kg), the control group was divided into one group with mild overweight (n = 15) and one lean control group (n = 14). Blood pressure, cardiac output, and calculated total peripheral resistance did not differ between the groups. LV mass was significantly increased (P < .05 to .01) in the two groups, with overweight, compared with the lean control group and in multivariate analysis body mass index (BMI), the primary determinant for LV mass (r = 0.63, P < .001). Neither LV contractility nor LV relaxation time index differed between the groups. Left ventricular distensibility (a/H ratio), which was moderately related to BMI, systolic blood pressure, and the renal vascular sensitivity to angiotensin II (r = 0.34, P < 0.03), was reduced compared with the control groups. This difference persisted after adjusting for BMI and blood pressure. The present study shows that in normotensive subjects with a positive family history of hypertension the increased LV mass was primarily dependent on weight, irrespective of heredity. However, the observed reduction in LV distensibility remained after adjusting for weight, suggesting that diastolic abnormalities may occur before hypertension in subjects likely to later develop the clinical condition.