Objective:To investigate the correlation between neuroendocrine(NE)differentiation and clinico-pathological features,prognostic factors of papillary thyroid carcinoma(PTC). Methods:The tissues of 103 PTC cases were amaylzed by HE staining,immunohisto-chemistry,immunogold labelling,biomarkers expression of neuroendocrine differentiation. Results:Thyroglobulin was positively expressed in PTC,while Calcitonin was negative. The larger tumor size of the cases with PTC accompanied with a higher NSE expression(P < 0.05). The higher degree of differentiation accompanied with a lower rate of CgA expression. The cases with nuclear inclusions showed obviously increased expression of CgA(P < 0.05). The degree of PTC cell differentiation and tumor size were associated with NE differentiation under TEM(P < 0.05). The CgA immunogold particles were scattered at the internal edge of NE particles within the cytoplasm of PTC cells. Conclusion:NE differentiation could occur in PTC,and NE differentiated cells could be derived from follicular epithelial cells instead of C cells. NE differentiation is correlated with tumor size,morphological change of nuclei and degree of differentiation in PTC. NE differentiation has no significant correlation with the prognosis of PTC.