This study was done to investigate the antioxidative effect of polygoni radix in Streptozotocin (STZ)-induced diabetic rats. Diabetes was induced by intravenous injection of STZ at a dose of 45 mg/kg dissolved in citrate buffer. The ethanol extract of Polygoni radix was orally administrated once a day for 7 days. The contents of Total cholesterol, triglyceride (TG) were significantly decreased in Polygoni radix treated STZ-sample group compared with to the those of STZ-control group. The hepatic cytosolic activities of glutathione-s-transferase (GST), superoxide dismutase (SOD) were significantly increased, Also the content of glutathione (GSH) was incresaed in Polygoni radix treated STZ-sample group compared with to the those of STZ-control group. but the content of malondialdehyde (MDA) and the hepatic cytosolic activity of Catalase (CAT) were decreaed but not statistical significant. These results indicated that ethanol extract of polygoni radix was effective for the antidxidative in the STZ-induced diabetic rats.