Background: Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) has been reported to beassociated with the development of various cancers. However, the role of TRAF6 in lung cancer remains unclear. Objective: To explore the expression and clinicopathological significance of TRAF6 protein in lung cancer tissues.Materials and Methods: Three hundred and sixty-five lung cancer samples and thirty normal lung tissues wereconstructed into 3 microarrays. The expression of TRAF6 protein was determined using immunohistochemistry(IHC). Furthermore, correlations between the expression of TRAF6 and clinicopathological parameters wereinvestigated. Results: The expression of TRAF6 in total lung cancer tissues (365 cases), as well as in small celllung cancer (SCLC, 26 cases) and non-small cell lung cancer (NSCLC, 339 cases) was significantly highercompared with that in normal lung tissues. The ROC curve showed that the area under curve of TRAF6 was0.663 (95%CI 0.570~0.756) for lung cancer. The diagnostic sensitivity and specificity of TRAF6 were 52.6% and80%, respectively. In addition, the expression of TRAF6 was correlated with clinical TNM stage, tumor size andlymph node metastasis in all lung cancers. Consistent correlations were also observed for NSCLCs. Conclusions:TRAF6 might be an oncogene and the expression of TRAF6 protein is related to the progression of lung cancer.Thus, TRAF6 might become a target for diagnosis and gene therapy for lung cancer patients.