Objectives : In order to study experimentally the effects of Woogwi-eum(Yougui-yin) on hypothyroidism, ${T_3}-uptake$ content, $T_3$ content, $T_4$ content, TSH content, hematological values, enzyme activity, total cholesterol content, $Na^{+}$ content change in the serum and body weight of rats induced by thiouracil were measured after medication of extract of Woogwi-eum (Yougui-yin). Methods : Sparque-Dawley rats were used in this experiment and the rats were divided into normal, control and experimental groups. The hypothyroidism of control and experimental groups was induced by thiouracil, Woogwi-eum(Yougui-yin) extract was orally administered in the experimental groups for 20 days Results : In this experiment, the Woogwi-eum(Yougui-yin) treated group showed a significant increase in the serum ${T_3}-uptake$, TSH, RBC and hematocrit content, whereas a significant decrease in the serum CPK, ALP, LDH, total cholesterol content and the body weight was measured. Conclusions : According to the above results, it is suggested that Woogwi-eum(Yougui-yin) is partially effective to the hypothyroidism induced by thiouracil in rats. Therefore, Woogwi- eum(Yougui-yin) seems to be applicable to hypothyroidism in clinical practice.