Objectives : The object of this study was to observe the pharmacological effects of Yookmijihwang-tang-gamibang (Liuweidihuang-tang-jiaweifang, YGB) consisted of 17 types of herbs has been traditionally used in Korean medicine for treating various disorders in clinics, aqueous extracts on the genetically obese and type II diabetic C57BL/6JHam-ob/ob(ob/ob) mice. Methods :Three different dosages of YGB were orally administered, once a day for 28 days to ob/ob mice with ob/ob control and C57BL/6JJms normoglycemic intact mice. Four weeks after treatments of YGB: the changes on the body weight, food consumption, blood glucose levels, leptin and adiponectin contents were observed for monitoring the antiobese and antidiabetic effects of YGB. The effects were compared to those of CLA(conjugated linoleic acid) which improve type II diabetes and inhibit related obesity. Results : After end of 28 days of continuous treatments, ob/ob control showed increases of adipocyte hypertrophy, vasodilated atrophic glomerulus which were detected with marked hyperplasia of pancreatic islets, insulin and glucagon producing cells. These obese and related type II diabetes induced in ob/ob mice were markedly and significantly inhibited by 28 days of continuous treatment of three dosages of YGB. The YGB 50mg/kg showed similar favorable effects on the diabetes and related diabetic complications as compared with CLA 750mg/kg in ob/ob mice of the present study. Conclusions : The results obtained in this study suggest that over 25mg/kg of YGB extracts favorably retarded the obese and type II diabetes in genetically obese and type II diabetic ob/ob mice.