In 38 patients with established essential hypertension and 32 age-matched normotensive control subjects proximal and distal arterial compliance were determined by computer-based assessment of the diastolic decay of a brachial arterial tracing and a modified Windkessel model of the circulation. In the hypertensive subjects compared to the normotensive subjects mean arterial pressure was 25% higher (P less than .001), systemic vascular resistance 23% higher (P less than .01), proximal compliance 19% lower (P less than .01), and distal compliance 72% lower (P less than .001). The reduction in distal compliance was highly age-dependent. In the youngest age range (45 to 54 years) little overlap appeared between hypertensive and normotensive groups, whereas in the oldest subjects studied (65 to 75 years) distal compliance was comparably low in the two groups. Thus, distal vascular compliance provides a sensitive and specific marker for the abnormal vasculature associated with hypertension and may be particularly useful in identifying the disease in young individuals with borderline blood pressure.