Objectives : The object of this study was to investigate the effects of Daeboeum-hwan (DBEH) aqueous extracts on Streptozotocin (STZ)-induced rat diabetes and related complications. Methods : SD rats were divided into 6 groups (n =8) : 50 mM citrate buffer and vehicle (distilled water 5 ml/kg) administered group (Intact control), STZ treatment (60 mg/kg, single intraperitoneally administered) and vehicle administered group (STZ control), STZ treatment and silymarin 100 mg/kg administered group (Reference), and STZ treatment and DBEH extracts 50, 100 and 200 mg/kg administered groups. DBEH extracts were orally administered once a day for 28 days from 3 weeks after STZ treatment. The results were compared with silymarin 100 mg/kg. Results : Decreases in the body weights, increase of kidney and liver weights, blood glucose, BUN, creatinine, AST, ALT, LDL, triglyceride and total cholesterol levels with decreases of HD L levels, increases of pancreatic MDA contents and decreases of GSH contents were detected in STZ control as compared with intact control. These diabetes and related complications were inhibited by treatment with 100 and 200 mg/kg of DBEH extracts. Conclusion : DBEH extracts showed favorable effects on STZ-induced diabetes and related complications mediated by their antioxidant effects as similar to silymarin. Because the lowest dosage (50 mg/kg) of DBEH treated group did not show any favorable effects as compared with STZ control, the effective dosages of DBEH is considered as about 100 mg/kg, while DBEH extracts at 200 mg/kg showed similar effects as compared with 100 mg/kg of silymarin. It, therefore, is expected that DBEH will show favorable effects on diabetes and various diabetic complications.