Effect of vitamins A and E derivatives on Fe-ascorbate dependent peroxidation was studied by means of thiobarbituric acid test in liposomes prepared from egg lecithin. Retinol, incorporated into liposomes at concentration less than 0.1 mol%, increases the lecithin oxidation, retinyl palmitate was less active and alpha-tocopherol inhibited the reaction. Synergistic effect of alpha-tocopherol and retinol was observed. After simultaneous administration of retinol and alpha-tocopherol into liposomes, vitamin A did not accelerate the lecithin oxidation but increased distinctly the inhibitory effect of alpha-tocopherol. This interaction did not occur between retinol and alpha-tocopherol acetate as well as between m-retinyl acetate and alpha-tocopherol. The data obtained suggest that vitamins A and E affect the lipid peroxidation not only via direct participation in free radical oxidation but also due to transformations of biological membranes structure.