Objective : The aim was to study experimentally the effects of Daeyoungjeon(DYJ) on the hypothyroidism of rats induced by thiouracil. Methods : Spargue-Dawley rats were separated into four groups. Except normal group, the other three groups were treated with thiouracil 0.50g/kg/days for 30 days by oral administration. Among the three groups, one group was treated DYJ extract 0.75g/kg/days for 20 days separately. Another group was treated DYJ extract 1.50g/kg/days for 20 days separately. T3-uptake, T3, T4, TSH, hematological values, enzyme activity, total cholesterol, triglyceride and Na+ content change in the Serum of rats were measured after medication of solid extract of DYJ. Results : As a result of this study, in the serum T3-Uptake and T4 level, hematological values and sodium were increased in DYJ group compared to control group. The serum TSH, total cholesterol, triglyceride, enzyme activity and body weight were decreased in DYJ group compared to control group. Conclusion : According to the above results, it is suggested that DYJ is effective to cure hypothyroidism.