Objective:To investigate the expression of CMET in papillary thyroid carcinoma(PTC) with cervical lymph node metastases, PTC without cervical lymph node metastases,follicular thyroid carcinoma and benign thyroid disease and the clinical significance. Methods:The expression level of CMET was examined by immunohistochemical analysis with CMET monoclonal antibody in 62 cases of PTC with cervical lymph node metastases, 50 cases of PTC without cervical lymph node mestastases, 10 cases of follicular thyroid carcinoma and 30 cases of benign thyroid disease. Results:PTC with cervical lymph node metastases expressed significantly greater level of CMET than the other forms of thyroid carcinoma and benign thyroid disease(P<0.001). CMET expression was significantly different for the following pairs of thyroid specimens:PTC with cervical lymph node metastases versus PTC without cervical lymph node metastases, P<0.001; PTC with cervical lymph node metastases versus follicular thyroid carcinoma, P<0.001; PTC with cervical lymph node metastases versus benign thyroid disease, P<0.001; PTC without cervical lymph node metastases versus follicular thyroid carcinoma, P=0.002; PTC without cervical lymph node metastases versus benign thyroid disease, P<0.001. The distributions of CMET expression were not significantly different for follicular thyroid carcinoma versus benign thyroid disease, P=0.015. Conclusions:Intense CMET expression is indicative of the presence of the cervical lymph node metastases and a marker of extracapsular spread and direct extension of PTC.It is significance for preoperative assessment of cervical lymph node metastases of PTC and in the choice of operative methods.