Abstract: Objective To study the expression of thyroid hormone receptor β1（TRβ1） in follicular thyroid carcinoma and adenoma and its clinical significance. Methods Expressions of TRβ1 in 54 follicular thyroid carcinoma patients and 45 follicular thyroid adenoma patients were detected by S-P immunohistochemistry.Clinicopathological data about the patients were analyzed. Results The positive expression rate of TRβ1 was significantly lower in follicular thyroid carcinoma than in follicular thyroid adenoma（16.7% vs 71.1%,P＜0.01）.The TRβ1 expression was significantly different in follicular thyroid carcinoma and adenoma due to their different TNM stage,size,lymph node metastasis,and distant metastasis（P＜0.05）. Conclusion TRβ1 is lowly expressed in follicular thyroid carcinoma and highly expressed in follicular thyroid adenoma,indicating that TRβ1 plays an important role in the pathogenesis of follicular thyroid carcinoma.TRβ1 expression is related with the size,lymph node metastasis,distant metastasis and TNM stage of follicular thyroid carcinoma,and can thus predict the prognosis of such patients.