This investigation was performed to study the antioxidant activities of Hovenia dulcis THUNBER var. koreana Nakai fruits extracts and the effect of Hovenia dulcis fruits extracts on glucose, lipid metabolism in diabetic rats. DPPH free radical scavanging activitiy and superoxide anion radical Scavenging of Hovenia dulcis fruits $80\%$ methanol extracts were $0.06pm0.002mg$ polyphrnol/ml and $0.l2pm0.00lmg$ polyphmol/ml, respectively. Hovenia dulcis fruits $80\%$ methanol extracts were partitioned into hexan, dichloro methane, ethyl acetate and butanol, successively. Ethyl acetate fraction were good antioxidant activity. Streptozotocin (45 mg/kg body weight, i.p.) induced diabetic rats showed a significant increases of plasma glucose, triglyceride and total cholesterol. Concomitantly significant decrease of plasma high density lipoprotein. Glutathione level were decrease in cytosol of liver. Lipid peroxide were increase in microsome of liver. Group 1 and 2 were treated with Hovenia dulcis fruits ethyl acetate extracts 50 mg/kg body weight and 20mg/kg body weight for 24 days, individually. Group land 2 rats showed decreased plasma glucose, triglyceride, total cholesterol and lipide peroxide in microsome of liver tissue of rats, and increased plasma high density lipoprotein and glutathione in cytosol of liver tissue rats. The result suggest that Hovenia dulcis THUNBER var. koreana Nakai fruits extracts may effectively normalize the impaired antioxiants status in streptozotocin induced diabetic rats. Hovenia dulcis fruits ethyl acetate extracts were used to improve the imbalance between free radicals and antioxidant system due to the diabetes.