The present study assessed the antioxidant properties of α -tocopherol, α -tocotrienol, and palm oil vitamin E, which contained 45% tocopherols and 55% tocotrienols. When vitamin E-deficient rats were fed either α -tocopherol- or α -tocotrienol-enriched diets, α -tocotrienol accumulated in the hearts and liver more slowly than α -tocopherol. The rate of lipid peroxidation induced in vitro in heart homogenate from rats supplemented with α -tocotrienol was approximately two-thirds as high as that from rats with an equivalent concentration of α -tocopherol. Thus palm oil vitamin E may be more efficient than α -tocopherol alone in protecting the heart against injury from ischaemia and reperfusion. In addition, supplementation with α -tocopherol or α -tocotrienol protects skeletal muscles against exercise-induced increases in protein oxidation Thus palm oil vitamin E protects biological systems against both lipid and protein oxidation.