To study the effect of Kamidaebotang on the hypothyroidism induced by thiourea in SD(Splague Dawley) rats, the weight of thyroid gland, the level of serum $T_3;and;T_4$. total cholesterol, hematological changes and histopathological findings were measured. The following results were obtained. 1. Thyroid gland weight of the Kamidaebotang B treated group was significantly increased as compared with that of control group(p<0.05). 2. The level of serum $T_3$ of the Kamidaebotang B treated group was slightly increased as compared with that of control group. But no significant changes appeared between two groups. 3. The level of serum $T_4$ of the Kamidaebotang A, B treated groups were significantly increased as compared with that of control group(p<0.05). 4. Total cholesterol of the Kamidaebotang A, B treated groups were not significant changes as compared with that of control group. 5. Hematological data of the Kamidaebotang A, B treated groups were not significant changes as compared with that of control group. 6. Histopathologically, Kamidaebotang B administration recovered effectly the dystropy, degeneration of thyroid follicle induced by thiourea. From above results, it is suggested that Kamidaebotang B is available to the hypothyroidism induced by thiourea in rats. Therefore, Kamidabotang B seems to be applicable to hypothyroidism in clinical practice.