The significance of age-related changes in arterial stiffness has remained largely uncertain in healthy subjects. This appears to be partly due to difficulties in the interpretation of methods for measuring arterial stiffness in vivo. Therefore, a recently developed electrical bioimpedance method was used for studying elastic properties of a vascular bed as a function of age. In 66 healthy subjects, aged 22-82 years, we investigated the vascular bed of an upper arm segment. This vascular bed showed an age-related decrease in the venous blood volume (r = -0.31, p& < 0.01) and in the distensibility, the inverse of stiffness, of the larger arteries (r = -0.38, p& < 0.001). The distensibility of the arterial bed as a whole at normotensive blood pressure, however, appeared to increase with age (r = 0.32, p& < 0.005). The arterial and venous blood volumes, arterial compliance and extravascular fluid volume were significantly higher in the males than in the females. Practically all investigated vascular properties appeared to be related with height, body mass or body mass index. We concluded that comparative studies concerning vascular properties should preferably be performed in subjects matched as to age, gender, height and body mass. In healthy subjects the smaller arteries adjust to the age-related decrease in large artery distensibility by means of an age-related increase in distensibility. These age-related changes in arterial distensibility are caused by changes in the females, and seem to be associated with age-related changes in body mass index rather than with aging per se.