The effects of vegetable oils („non-erucic-acid” rapeseed oil and sunflower oil) and animal fat (butter) on the development of experimental atherosclerosis were studied in rabbits kept during 12 weeks on a cholesterol-rich diet. The degree of atherosclerotic changes by calculating planimetrically the site of the areas of fatty infiltrations in the aorta, the concentrations of total cholesterol, HDL-cholesterol, triglycerides lipid peroxides in the serum and ascorbic acid content in the tissues was determined. The cholesterol-rich diet caused development of atherosclerotic changes, increased serum cholesterol and lipid peroxide levels and ascorbic acid concentration in the studied tissues. „Non-eru- cid-acid” rapeseed oil slowed down the development of experimental atherosclerosis in a degree comparable to the effects of sunflower oil.