Effects of Sotosaja hwan on Blood Glucose, Hyperlipidemia, Polyol Pathway and Antioxidative Mechanism in ob/ob Mouse Diabetes is a disease in which the body does not produce or properly use insulin. Etiological studies of diabetes and its complications showed that oxidative stress might play a major role. Therefore, many efforts have been tried to regulate free oxygen radicals for treating diabetes and its complications. Sotosaja-hwan has been known to be effective for the antiaging and composed of four crude herbs. In male ob/ob mouse in severe obesity, hyperinsulinemia and hyperlipidemia, which are features of NIDDM, the hyperglycemic activites and mechanisms of Sotosaja-hwan were examined. Mice were grouped and treated for 5 weeks as follows. Both the lean (C57/BL6J black mice) and diabetic (ob/ob mice) control groups received standard chow. The experimental groups were fed with a diet of chow supplemented with 30 and 90 mg Sotosaja-hwan per 1 kg of body weight for 14 days. The effects of Sotosaja-hwan extract on the ob/ob mice were observed by measuring the serum levels of glucose, insulin, lipid components, and the kidney levels of superoxide anion radical $({cdot}O_2)$, MDA+HAE, GSH/GSSG ratio, and also the enzyme activities involved in polyol pathway. Sotosaja-hwan lowered the levels of serum glucose and insulin in a dose dependent manner. Total cholesterol, triglyceride and free fatty acid levels were decreased, while the HDL-cholesterol level was increased, in Sotosaja-hwan treated groups. Renal aldose reductase and sorbitol dehydrogenase activities were increased in the ob/ob mice, whereas those were inhibited in the Sotosaja-hwan-administered groups. Sotosaja-hwan inhibited the generation of ${cdot}O_2$ in the kidney. Finally, MDA+HAE levels was increased and GSH/GSSG ratio was decreased in the ob/ob mice, whereas those were improved in the Sotosaja-hwan-administered groups. Sotosaja-hwan showed the antidiabetic and anti hyperlipidemic activities by regulating the activities of polyol pathway enzymes, scavenging reactive oxygen species and reducing the MDA+HAE levels in the ob/ob mice.