Oxidative damage has been proposed as one of the possible mechanisms involved in the development of dialysis-related complications. Strengthening the defense system by supplementing antioxidants may provide protection against oxidative damage. Therefore, this study was carried out to investigate oxidant and antioxidant status in chronic renal failure patients undergoing hemodialysis and the effect of UbiQ100 supplementation on oxidant and antioxidant status. The blood samples were analyzed for quantitation of MDA as index of lipid peroxide, nitric oxide, vitamin E and erythrocyte superoxide dismutase activity. Significantly increased levels of serum lipid peroxide and decreased levels of nitric oxide, vitamin E, and erythrocyte superoxide dismutase activity were noticed in the patients both before and after hemodialysis, as compared to control subjects. However, significant reduction in lipid peroxide and improvement in nitric oxide, vitamin E and erythrocyte superoxide dismutase activity were observed after supplementary treatment of UbiQ100.