Objective To examine the diurnal variability in arterial distensibility and compliance and to study the effects of exercise training on these large artery properties. Design Vessel wall properties of the elastic common carotid and muscular brachial arteries were measured non-invasively with a vessel wall movement detector system in 12 healthy volunteers. Properties of the common carotid, the femoral and the brachial arteries were studied in 15 sedentary males in comparison with 15 male cyclists. Results Diurnal changes in the carotid and brachial arteries were similar. Blood pressure decreased at night while arterial diameter increased. Distensibility decreased and compliance was preserved at night. The vessel wall properties of the carotid artery did not differ between the sedentary males and the cyclists, but the femoral and brachial arteries were more elastic in the cyclists. The diameter of the femoral artery was larger in the cyclists. Conclusions We found a diurnal pattern in changes in diameter and distensibility of elastic and muscular large arteries. Compliance, the buffering capacity of larger arteries, was preserved at night. The supplying femoral artery was larger and more distensible in cyclists. Exercise training did not affect the elastic carotid artery, but improved vessel wall properties of the brachial, and maybe also of other, muscular large arteries.