The purpose of this study was to compare the plasma levels of the anti-oxidant system and oxidative stress between a cervical neoplasia group and a normal control group and to investigate the relationship between the levels of micronutrients of antioxidant system and various clinicopathological parameters of cervical carcinoma. A cross-sectional sample of 180 women, including 90 normal controls, was recruited from November 2000 to January 2001. Plasma concentration of malondialdehyde (MDA) was spectrophotometrically measured as the parameter of lipid peroxidation. Plasma levels of antioxidant vitamins were analyzed with the help of reverse-phase, high-pressure liquid chromatography, whereas glutathione peroxidase activity was evaluated by using coupled enzyme procedure. While the activity of glutathione peroxidase and the plasma levels of antioxidant vitamins, such as lutein, beta-carotene, lycopene, and zeaxanthin, were all significantly lower, the concentration of MDA was significantly higher in women with cervical intraepithelial neoplasia (CIN) or invasive cervical cancer, compared to those of the normal control group. The status of the plasma antioxidant system showed no significant correlation with the prognostic factors of cervical cancer. These findings suggest a potential role of oxidative stress-induced lipid peroxidation and the impairment of the anti-oxidant system in the pathogenesis of CIN and carcinoma of the uterine cervix.