Objective To investigate the expression and clinical significance of ubiquitin-specific protease 9X (USP9X) protein in non-small cell lung cancer (NSCLC). Methods USP9X proteins were detected in 71 cases of NSCLC and 20 cases of benign pulmonary tissues by immunohistochemical staining. The correlation between USP9X expression and 51 NSCLC clinicopathological parameters as well as survival rates were indicated. Results Higher rate 〔69.0% (49/71)〕 of the expression of USP9X was observed in NSCLC samples, compared with 20.0% (4/20) in benign pulmonary tissues (PPPP