: Vascular aging can be assessed by arterial stiffness measured through pulse wave velocity (PWV). Increased PWV predicts arterial hypertension, cardiovascular events and all-cause mortality. Detection of early signs of vascular aging remains an unmet problem. To search for the most sensitive markers for the early increase in vascular stiffness in a healthy population. : One-hundred and twenty healthy subjects were divided in three equal age groups: <30 years, 30-45 years and >45 years. Head-up tilt test (HUTT) protocol was applied, providing a standardized hydrostatic column height. PWV at the brachial-ankle artery site (baPWV) was measured using a multichannel sphygmomanometer ABI System 100 PWV in three positions: in the baseline horizontal (supine) position-baPWVb; during the head tilt-up with an individual angle of inclination-baPWVt; and when returning to supine. : The most sensitive marker of early stiffness increase in a healthy population is the relative orthostatic increase in baPWV, ΔbaPWV/baPWVb, where ΔbaPWV = baPWVt - baPWVb. The significance of differences in this parameter between the young and elderly groups reached = 0.000075 and = 0.000006, respectively. : The proposed index ΔbaPWV/baPWVb can be considered as a promising sensitive early biomarker of vascular aging and as a potential effective indicator in cardiovascular prevention. A longitudinal cohort study is needed to confirm this assumption.