Investigations were carried out on 40 rabbits divided into 4 equal groups: group 1 - control, group 2-high-fat diet (HFD) containing cholesterol and coconut oil, group 3 - HFD + oats chaff extract (l vena sativa L. - AS) , group 4 - HFD + rutin. The experiment lasted 12 weeks. Lipid fractions, testosterone, insulin and malondialdehyde concentrations were assayed in the blood. In the liver the content of cholesterol, free ascorbate radicals and cytochrome P-450 were determined. Besides, the aortic intima was grossly evaluated and the percentage of surface of intima covered by atherosclerotic plaques was measured planimetrically. In the group receiving AS, the concentration of total cholesterol, LDL-cholesterol and ß-lipoproteins was markedly decreased, while the concentration of HDL fraction was elevated. The diminished concentration of testosterone in group 2, was normalized under the influence of AS. Similarly the concentration of cytochrome P-450 in liver microsomes behaved. In animals receiving AS, the diminution of the aortic intima covered by the atherosclerotic plaques, was statistically significant. The obtained results suggest, that the oats chaff extract, may play an appreciable role in the prophylaxis and management of atherosclerosis.