BACKGROUND Immunotherapy has shown promising effect for non-small cell lung cancer (NSCLC) patients. Yet the biomarkers for predicting immunotherapy efficiency are still lacking. METHODS We tested 139 surgical resected NSCLC primary tumor samples from Medical University of Gdansk, Poland, for T cell immunoglobulin and mucin-domain containing-3 (TIM-3) level by immunohistochemistry (IHC), analyzed the expression of TIM-3 protein on NSCLC tumor cells and tumor infiltrating lymphocytes (TILs). RESULTS TIM-3 on TILs was correlated with programmed cell death protein-1 (PD-1) on TILs (correlation coefficient =0.346, P<0.001) and programmed cell death protein-ligand 1 (PD-L1) on TILs (correlation coefficient =0.313, P<0.001), PD-L1 level on tumor cells (correlation coefficient =0.255, P=0.002), TIM-3 level on tumor cells (correlation coefficient =0.262, P=0.002) and TIL percentage (correlation coefficient =0.172, P=0.043). TIM-3 level on tumor cells only had correlation with PD-L1 level (correlation coefficient =0.170, P=0.045). High level of TIM-3 on TILs indicated shorter recurrence-free survival (RFS) and overall survival (OS) (RFS 1.800 years, 95% CI, 1.230-2.370 vs. 0.870 years, 95% CI, 0.212-1.528, P=0.048) (OS 2.960 years, 95% CI, 2.268-3.652 vs. 1.080 years, 95% CI, 0.228-1.932, P=0.034). CONCLUSIONS TIM-3 is expressed on NSCLC tumor cells and TILs in all NSCLC pathological type. TIM-3 level on TILs had correlation with PD-1 and PD-L1 level. NSCLC patients with high TIM-3 level on TILs were more likely to have poor prognosis.