Iron plays a promoting role in lipid oxidation through several mechanisms. Therefore, hepatic iron deposits in the rat may lead to peroxidative damage and to alterations in the lipoprotein formation. In this report we observed that an iron overload in rats strongly reduced the hepatic lipoprotein secretion but did not affect oxidation resistance of native lipoproteins and erythrocyte lipids in spite of tocopherol and ascorbate deficiencies. Since oxidation resistance depends on the substrate to antioxidant vitamin molar ratio, our results show that an iron overload probably alters the lipoprotein lipid fatty acid composition in rats.