We assessed the effects of calcium ion (Ca++) entry blockade (nifedipine) on the static elastic properties of the thoracic descending aorta in 60 subjects classified into 4 groups according to age and complications. The stiffness index (beta), which expresses the mechanical properties of the arterial wall, was calculated from the dimensional changes of the thoracic aorta by transesophageal echocardiography and blood pressure was determined by conventional cuff method. After administration of nifedipine, beta was significantly decreased in all groups. There was a significant correlation between beta at rest and the value of a decrease in beta after nifedipine in the relatively younger and the older groups with complications, but no significant correlation was observed in the older group without complications. Nifedipine directly reduces the stiffness of the descending aorta. The effect is stronger in relatively younger subjects, especially in subjects with risk factors of atherosclerosis and stiff descending aorta at rest. These results suggest that there may be a reversible sclerotic property of the descending aorta, probably caused by high smooth muscle tone before an irreversible atherosclerosis occurs in patients with risk factors promoting atherosclerosis.