Objective: To determine any association between plasma coenzyme Q 10 (CoQ 10) and α-tocopherol levels and severity of cervical intraepithelial neoplasia (CIN) and cervical cancer. Methods: Plasma levels of total CoQ 10 and α-tocopherol were measured by high-performance liquid chromatography in patients with biopsy-confirmed CIN (n = 55) and cervical cancer (n = 20) and in normal women with no abnormal Pap test results (n = 27). Cervicovaginal lavages containing epithelial cells (CVC), obtained from the same subjects, also were analyzed for CoQ 10 concentrations. Results: The mean plasma levels of CoQ 10 and α-tocopherol were significantly ( P = 0.001) lower in patients with CIN and cervical cancer compared with controls. Levels of CoQ 10 from CVC were measurable and also were significantly ( P = 0.001) lower in women with CIN. Conclusion: The findings suggest that CoQ 10 and α-tocopherol antioxidants may play a role in the pathogenesis of CIN. The decrease in CoQ 10 and α-tocopherol levels may be caused by deficient dietary intake in women with CIN. Alternatively, low antioxidant levels may reflect increased utilization to counteract oxidative stress.