To optimize the adequate atherogenic diet composition for nutritional atherosclerosis studies utilizing B6.KOR-Apoe(shl) mice, we investigated the effect of dietary cholesterol, AIN formula, and dietary fats on the development of atherosclerosis. Cholesterol supplementation (0.15-2%) for 12 weeks resulted in a dose-dependent increase in the development of atherosclerosis. Furthermore, there were no significant differences in the degree of atherosclerosis between B6.KOR-Apoe(shl) mice fed a modified-AIN-76 diet and those fed a modified-AIN-93M diet containing corn oil or soybean oil for 10 and 12 weeks. The present experiment indicates that the adequate dietary level of cholesterol was 0.15%, and that further studies are necessary to determine the optimal level of various types of dietary oils for nutritional atherosclerosis experiments in B6.KOR-Apoe(shl) mice.