The aim of this research was to identify any early cardiovascular changes that may be predictive of future hypertension in young subjects with family history of hypertension. The study was conducted on 25 offspring of hypertensive parents, mean age 17 years (22 with hypertension only in 1 parent and 3 with both hypertensive parents) and 20 offspring of both normotensive parents, matched by age. Subjects were divided into children (7-13 years) and young adults (19 years on). All subjects underwent three office blood pressure measurements with a mercury sphygmomanometer. On the third control, BoMed thoracic electrical bioimpedance at rest and during upright bicycle exercise was performed. Physical characteristics were similar in subjects matched by age in the two groups. Systolic blood pressure was similar in offspring of normotensives and hypertensives, both at rest and during exercise; diastolic blood pressure was greater in offspring of hypertensive parents at rest (73.1 +/- 10.5 vs 63.5 +/- 7.1 mmHg, p < 0.05), during the first minutes of exercise and during the recovery phase (p < 0.05). Moreover, at the third blood pressure measurement at rest, diastolic blood pressure decreased, with respect to the first measurement, only in children and young adult offspring of normotensive parents, while systolic blood pressure decreased in the two groups of child subjects. No differences in heart rate were observed, both at rest and during physical exercise, between offspring of normotensives and hypertensives. Left ventricular end-diastolic volume, stroke volume, ejection fraction, cardiac output and systemic vascular resistance at rest and their response to decubitus changes and exercise were normal and similar in offspring of normotensive and hypertensive parents both in children and young adults. In conclusion, a different behavior of diastolic blood pressure was found in offspring of hypertensive parents compared to that of normotensive parents, both in children and, to a higher degree, in young adults. This may be an expression of early vascular change in subjects with a genetic predisposition to hypertension.