Experimental hyperlipidemia and atherosclerosis induced by a cholesterol diet in SPF male and female rabbits (JW/KBL) were investigated by the determination of the lipid contents of the plasma, liver and thoracic aorta; determination of morphological changes of the aortic arch by head angiography; and computer tomography of the brain. Rabbits were fed the diet that contained 1% cholesterol for eight weeks. The plasma lipid levels began to rise from two weeks after the cholesterol diet was started, reached the peak four to six weeks later, and then fell in both males and females at eight weeks. The cholesterol of the high density lipoprotein in male rabbit plasma was slightly increased by the cholesterol diet, but not in female rabbits. An increase in the total cholesterol (TC) and triglyceride contents of the liver and an increase in the TC and phospholipid contents of the thoracic aorta were observed at the eighth week. Histological examination of the aortic arch showed marked lipid vacuoles under the endothelial cells, noticeable lipid inclusions in the smooth muscle cells of the intima and granular prominences on the internal surface of the aorta. Head angiography of rabbits fed the cholesterol diet revealed a constriction of the lumina of several arteries due to the lipid depositions. These results suggest that hyperlipidemia and atherosclerosis can be produced at the eighth week using SPF rabbits fed on a cholesterol diet.