T-cell immunoglobulin- and mucin domain-3-containing molecule 3 (TIM-3) is a membrane protein expressed in various kinds of immune cells and plays a pivotal role in immune regulation. Recently, TIM-3 was reported to be expressed aberrantly in melanoma cells, contributing to the low adhesion ability of tumor cells and promoting the survival of melanoma cells. We investigated TIM-3 expression in non-small cell lung cancers (NSCLCs), and further analyzed whether the aberrant expression of TIM-3 is related to the prognosis for patients with lung cancer. Tumor tissue samples from 30 patients with NSCLC were involved. Results of immunohistochemical analysis showed that TIM-3 stained positive on tumor cells in 86.7% (26/30) patients with primary NSCLC. The TIM-3 expression in NSCLC tumor cells was correlated with histologic type and pathologic T classification of the disease (P < .05). More importantly, patients with TIM-3-positive tumor cells had a significantly shorter survival time than those with TIM-3-negative tumors. Multivariate analysis demonstrated the significant role of TIM-3 expression in tumor cells as an independent prognostic factor for patients with NSCLC (relative risk, 4.481; 95% confidence interval, 1.790-11.22; P = .0005). Our results suggest that the ectopic expression of TIM-3 in tumor cells may be a potential, independent prognostic factor for patients with NSCLC.