ObjectiveTo investigate the expressions of Snail and N-cadherin protein in thyroid papillary carcinoma (PTC) tissues and cell lines, and then discuss the clinical value of Snail and N-cadherin expressions. MethodsImmunohis-tochemical SP technique was performed to detect the expressions of Snail and N-cadherin protein in 60 cases of PTC, and the relation between the expression of Snail or N-cadherin and clinicopathologic indicators was analyzed. Western blot was used to investigate the constitutive and inducible expressions of Snail and N-cadherin protein. Results①The positive rates of Snail and N-cadherin protein expressions were 85.0% (51/60) and 78.3% (47/60) respectively in the PTC tissues of 60 patients with PTC, which were significantly higher than those (0, 0, respectively) in the corresponding normal tissues adjacent to the cancer (P < 0.01).②The positive rates of Snail and N-cadherin protein expressions in the PTC with lymph node metastasis were significantly higher than those in the PTC without lymph node metastasis (P < 0.01), which were not related with the gender, age, tumor size of the patients (P > 0.01).③There was a positive correlation between Snail and N-cadherin protein positive expression (rs=0.721, P < 0.001).④The constitutive and inducible expressions of Snail and N-cadherin in the PTC tissues and cell lines further were identified by Western blot. ConclusionsSnail and N-cadherin could constitutively express in PTC, which might play important roles in the development and metastasis of PTC. Snail and N-cadherin might be used as effective indicators.