Objectives : The object of this study was to observe the effects of Hwangryungeehwang-tang (HRGHT), which has traditionally been used in Korean medicine for treating diabetes, by administering aqueous extracts to streptozotocin-induced diabetic rats. Methods : Three different dosages of HRGHT extracts were orally administered once a day for 28 days from 3 weeks after streptozotocin treatment (60 mg/kg, single intraperitoneally administered). 6 groups, of 8 rats per group were used in the present study, selected 3 weeks after streptozotocin treatment based on blood glucose levels and body weights. Changes to the body weights, blood glucose levels, serum low density lipoprotein (LDL), high density lipoprotein (HDL), triglyceride and total cholesterol levels were observed, as well as changes on the pancreatic, hepatic and kidney malondialdehyde (MDA) contents for lipid peroxidation and glutathione contents for antioxidant effects. The results were compared with a potent antioxidant silymarin 100 mg/kg, of which the effects on streptozotocin-induced diabetes and related complications are already confirmed. Results : Significant decrease of blood glucose levels, serum LDL, total cholesterol, triglyceride levels, pancreatic, hepatic and renal MDA contents and significant increase of body weights, serum HDL levels, pancreatic, hepatic and renal GSH contents were detected in HRGHT extracts 100 and 200 mg/kg administered groups as compared to the streptozotocin control group. The lowest dosage of HRGHT treated group, 50 mg/kg, did not show any favorable effects as compared with the streptozotocin control. Conclusions : HRGHT has favorable effects on diabetes and related hyperlipidemia. Therefore, more detailed mechanism studies should be conduced in future with efficacy tests of individual herbal compositions of HRGHT and screening of the biological active compounds in the herbs.