Abstract: Objective To investigate the correlation of microRNA-155 (miR-155) expression with clinicopathological features of patients with papillary thyroid carcinoma (PTC) and explore the value of miR-155 in prognostic assessment of PTC. Methods We collected 86 pairs of fresh PTC and adjacent tissues to examine the expression of miR-155 using fluorescent quantitative PCR. miR-155 expressions in the tissues were analyzed in relation to the clinicopathological features of the patients. Results Compared with the paired adjacent tissues, 69.8% (60/86) of the PTC tissues showed up-regulated miR-155 expression by 2.63± 2.73 folds. Up-regulated miR-155 expressions were associated with a larger tumor size (1.66±0.96 vs 1.19±0.52 cm, P=0.021), a higher likeliness of extrathyroid invasion (56.7% vs 23.1%, P=0.004), a higher rate of lymph node metastasis (70% vs 46.2%, P= 0.036), a more advanced TNM stage, and a higher rate of III-IV stage of the tumor (20% vs 0%, P=0.014). The expression level of miR-155 in PTC tissues was positively correlated with lymph node metastasis (r=0.531, P=0.001). Conclusion PTC patients with miR-155 over-expression tend to have a greater tumor size, a greater likeliness of extrathyroid involvement, a higher rate of cervical lymph node metastasis and a more advanced TNM stage. The high expression of miR-155 in the tumor may indicate a poor prognosis of PTC patients.