Aging in mammalian species appears to be the result of normal developmental and metabolic processes. In spite of the vast complexity of aging processes, relatively less complex processes such as longevity determinant genes (LDGs) may exist governing aging rate. Much experimental data exists indicating a causative role of oxyradicals in aging processes. In testing the hypothesis that antioxidants may represent LDGs, a positive correlation in the tissue concentration of specific antioxidants with life span of mammals was found. These antioxidants include superoxide dismutase, carotenoids, alpha-tocopherol, and uric acid. We also found that the resistance of tissues to spontaneous autoxidation and the amount of oxidative damage to DNA correlates inversely with life span of mammals. These results suggest a role of oxyradicals in causing aging and that the antioxidant status of an individual could be important in determining frequency of age-dependent diseases and duration of general health maintenance.