Living organisms have antioxidant enzymes, such as superoxide dismutase, catalase SE glutathione peroxidase, that protect themselves from the toxic effect of superoxide free radicals. Some report says that intracellular oxidation stress is involved in pathogenesis of chronic complications of diabetes mellitus. This study was performed to evaluate the effect of red ginseng on lipid peroxidation of red blood cell and antioxidant SOD activity of serum in NIDDM patients. As a result, there were trends for decrease of lipid peroxidases of RBC and Increase of SOD activity of serum in ginseng group but that were not statistically significant. Therefore, we suggest long term and large sized control study is necessary to confirm the protective effects of red ginseng on oxidative damage in NIDDM patients.