We investigated local pulse wave velocity (LPWV) in different aortic segments with respect to the rheological properties of the aorta with age-related progression of atherosclerosis in Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits. Normal and KHC rabbits aged 10-12, 22-24 and 34-36 months were anesthetized with pentobarbital sodium (30 mg kg(-1), intravenous). Pulse waves at the ascending aorta were recorded simultaneously with those at the proximal, middle and distal thoracic and abdominal aortas by moving a catheter with three micromanometers (40-mm intervals) at 80-mm intervals from the origin of the descending thoracic aorta. The aortic diameter was measured using an intravascular imaging system at the same aortic position at which the pulse waves were measured. LPWV was the greatest in the aortic arch, decreased gradually in the thoracic aorta and increased again in the abdominal aorta in KHC rabbits, whereas it was the lowest in the aortic arch, increased slightly in the thoracic aorta and increased gradually in the abdominal aorta in normal rabbits. LPWV increased significantly with age in most aortic segments. The change pattern of LPWV resembled that of the percent fractional lesioned area where LPWV was determined. The significant increase in LPWV with age was mainly due to the increase in the elastic modulus of the aortic wall with atherosclerotic progression as well as the increase in wall thickness. LPWV accurately detected the presence of atherosclerotic lesions and alteration in the rheological properties of the aortic regions through which pulse waves travelled.