Evidence suggests that reactive oxygen species in brain may play a role in the development of age-related neuronal impairments, and that the increase in the concentration of the proinflammatory cytokine, interleukin-1β (IL-1β), in aged brain tissue, may also be a contributory factor. In this study, we have analyzed changes in enzymatic and nonenzymatic antioxidant levels, in parallel with interleukin-1β concentration, in cortical tissue prepared from young and aged rats. We report that there was an age-related increase in the activity of superoxide dismutase without concomitant changes in the activity of catalase or glutathione peroxidase and an age-related decrease in the concentrations of α-tocopherol and ascorbate. These observations, coupled with age-related increases in lipid peroxidation and interleukin-1β concentration, are consistent with a compromised antioxidant defense in cortex of aged rats, a proposal supported by the finding that these changes were not observed in cortical tissue prepared from rats fed on a diet supplemented with α-tocopherol and ascorbate for 12 weeks.