Serum cholesterol level increased sharply in rabbits fed an atherosclerosis-promoting diet containing 0.25% or 0.5% cholesterol. Oral supplementation with 2100 IU of vitamin E per week manifested a hypocholesterolemic effect only after four weeks, with 50% reduction attained on the 8th week. Changes in low density and very low density lipoprotein cholesterol levels paralleled those in the serum. Liver total cholesterol level and the ratio of free to ester forms were not different between vitamin E-supplemented and nonsupplemented rabbits, whereas a 4-5 fold increase in hepatic cholesterol-7 alpha-hydroxylase activity, elevation of bile salt concentration and improvement in bile lithogenic index were observed in the vitamin E-supplemented groups.