The inhibitory effect of elastase on calcification in liver, kidney and the central nervous system (CNS) was studied in rabbits with atherosclerosis induced by a cholesterol-rich diet. A total of 25 male rabbits were divided into six groups. In the first three groups, rabbits received a standard diet, a 1.5% cholesterol-rich diet or a 1.5% cholesterol-rich diet with intraperitoneal elastase (450 IU/kg.day) for 3 months. In the second three groups, rabbits received a standard diet, a 0.67% cholesterol-rich diet or a 0.67% cholesterol-rich diet with intraperitoneal elastase (450 IU/kg.day) for 6 months. Tissue calcium levels were then determined by neutron activation analysis. Tissue lipid levels were also measured. Dietary cholesterol increased serum lipid levels, atherosclerotic lesions and calcium levels in the CNS, but not in the liver or kidney. Calcium levels in the cerebellum and spinal cord of rabbits receiving the 0.67% cholesterol-rich diet plus elastase were significantly lower than those of rabbits receiving the 0.67% cholesterol diet alone. Elastase had a gradual inhibitory effect on the increase in calcium levels in CNS of cholesterol-induced atherosclerotic rabbits, reduced the increase in serum lipids and decreased the incidence of atherosclerotic lesions.