Objective : This study was to elucidate the effects of Hyunsamkabhangbang (HSK) on the hyperthyroidism induced by sodium levothyroxine. Method : Sprague-Dawley rats were separated into five groups. Except the normal group, the other four groups were treated with sodium levothyroxine 160${mu}g/kg/day$ for 5 days by oral administration. Among the four groups, all except one (as control) were treated with various concentrations of HSK (0.5, 1.0, 2.0 g/kg/days) for 3 days separately. T3-uptake, T3, T4, TSH, total cholesterol, free fatty acid, ${eta}$-lipoprotein, glucose, ALP, AST, ALT change in the serum and body weight of rats were measured after medication of solid extract of HSK. Results : HSK decreased significantly serum T3, T4, T3-uptake, ALP, free fatty acid and glucose level in a dose-dependent manner compared with control. HSK increased significantly serum TSH and total cholesterol level and body weight in a dose-dependent manner compared with control. HSK also increased serum ${eta}$-lipoprotein level compared with control, but not statistically meaningfully. HSK increased significantly serum AST and ALT level compared with control, but relationship to hyperthyroidism is not found. Conclusions : From these results, it could be concluded that HSK lowers excess thyroid hormone and increased metabolism, resulting in improvement of hyperthyroid state.