All aerobic cells form free radicals. During respiration, univalent reactions of oxygen are preferred, producing superoxide radicals (O~-), hydrogen peroxide (H202), and hydroxyl radicals (OH'). Additional OH" radicals and singlet oxygen (102) form following reactions with metal catalysts. Complex defenses exist in cells as protection against the consequences of free radical formation (Siesjo, 198l). Each of our cells is protected by an extremely effective network of antioxidant mechanisms. These defenses include enzyme scavengers, such as superoxide dismutase, catalase, and peroxidase, in most cells. These quench superoxide anions, hydrogen peroxide, and lipid peroxides, respectively. There are also endogenous scavengers of free radicals. Chief among these is e-tocopherol. Others include ascorbic acid and thiol-containing compounds. Cellular organization serves to minimize contact between free radical reactions and sensitive molecules. The most abundant and effective antioxidants in biological systems are the tocopherols. Vitamin E was originally discovered as an essential factor in the reproduction of rats. The active substance, now known as e-tocopherol, was found to be a powerful antioxidant as well. Whether the latter explains the vitamin activity remains a topic of debate. Much remains to be learned about the metabolic properties of tocopherol, but it is within the context of antioxidants that current interest in the tocopherols is centered. The goal of this review is to feature the tocopherols and antioxidant metabolism as these relate to the brain and nervous system. General properties and