OBJECTIVES: Compared to normal subjects hypertensive patients have an increased radial artery isobaric distensibility, contrasting with a decrease in elasticity of large arteries and systemic compliance. To address the question whether elasticity is increased in response to long-standing elevated blood pressure or is present at an early stage of the disease, we compared normotensive offspring of hypertensive parents with control subjects. Furthermore, enhanced sympathetic response to mental stress was demonstrated in individuals predisposed to hypertension and might contribute to the elevation of blood pressure via a peripheral mechanism. Thus, an abnormal vasoconstrictive response of the radial artery to psychological stress was sought in these subjects. DESIGN: The geometry and the elastic porperties of the radial artery were assessed in normotensive offspring of hypertensive and normotensiven parents at baseline and during mental stress. METHODS: A high-precision echo-tracking ultrasound device was combined with photoplethysmography for continuous measurement of radial artery diameter and isobaric distensibility in 18 normotensive offspring of parents with essential hypertension and 18 control subjects under resting conditions and during a 3-minute mental stress test. RESULTS: Baseline arterial distensibility and compliance were comparable in offspring of hypertensive and normotensive parents. During mental stress, blood pressure and heart rate increased similarly in both groups. Adrenergic activation did not alter the elastic properties of the radial artery in the individuals with a genetic predisposition to essential hypertension. CONCLUSIONS: There was no alteration in elastic properties of the radial artery in normotensiven individuals at genetic risk to develop arterial hypertension. Furthermore, mental stress did not abnormally increase the vascular tone of this medium-sized muscular artery in these subjects as compared to controls. This indicates that functional and/or structural vascular alterations do not precede a distinct rise in blood pressure or abnormal blood pressure reactivity in subjects prone to develop essential hypertension.