Autoantibodies against oxidized DNA bases are found in vivo and have been used as an indicator of oxidative damage, yet little is known concerning their individual variation and relation to serum micronutrients. Human plasma anti-5-hydroxymethyl-2'-deoxyuridine (HMdU) autoantibody (aAb) levels were repeatedly determined in 41 women and 11 men, and found to have small within-individual variation over time, but large between-individual differences. A positive association in both women (r = .5762, p = .0001) and men (r = .415, p = .2) between plasma total tocopherols and antibody levels was observed. Autoantibody levels were lower in postmenopausal women (8.37 +/- 1.61 vs. 17.18 +/- 2.85 in premenopausal women, p < .01), independently of plasma tocopherol. However, aAb titers in postmenopausal women were still significantly associated with plasma tocopherol levels and adjustment for menopausal status in women yielded a highly significant correlation between HMdU aAb levels and total tocopherol (r = .7342, p = .0001). Plasma malondialdehyde equivalents (MDA), a measure of lipid peroxidation, were also higher in individuals with either high plasma alpha-tocopherol or high beta+gamma-tocopherol levels. The positive association of tocopherols with markers of oxidative damage may reflect a response to the generation of endogenous oxidants associated with enhanced immune function. The decrease in aAb level in postmenopausal women may similarly reflect decreased immune function associated with decreased estrogen levels.