The effect of cholesterol feeding and elastase administration on the arterial stiffness and elastic properties was investigated in rabbits by pressure-diameter tests on excised thoracic aortas, common carotid and femoral arteries. Rabbits in groups RA and RB were fed 1% cholesterol diet for 14 weeks. Groups RC and RD were fed the cholesterol diet for the first 7 weeks, and then given regular chow for the last 7 weeks. In addition, rabbits in groups RB and RC were administered elastase daily for the last 7 weeks. Rabbits in group RE were fed the regular chow for 14 weeks and served as the control group. The arterial stiffness and the elastic modulus of wall material in the RA rabbits were generally higher than those in the control rabbits. Administration of elastase and/or feeding of the regression diet decreased the wall stiffness and elastic modulus significantly, although the effect of elastase did not appear clearly when used in combination with the regression diet. The cholesterol feeding decreased the ratio of thickness to wall radius, whereas the ratio was more or less increased by the elastase administration and/or the regression diet.