Objective: To analyse the recent findings regarding programmed-death ligand 1(PD-L1) expression on tumor infiltrating immune cells in NSCLC and its potential role as a predictive biomarker for clinical outcomes and for successful PD-1/PD-L1 blocking immunotherapy. Methods: 5 databases were accessed for search: PubMed, Web of Science, Scopus, Lilacs, and Clinical Trials.gov. Articles were selected if written in English, Portuguese or Spanish and if available via institutional access. Results: 15 articles were selected. PD-L1 expression was found to be related to the presence of immature DCs and had also constitutive expression on fibroblasts derived from NSCLC specimens. PD-L1 expression in tumor infiltrating immune cells was observed to be correlated with overall survival benefit and improved tumor response after atezolizumab therapy. A significant correlation between PD-L1 expression in peripheral T cells and clinical outcomes was also detected, besides the finding of significant correlation between an increased PD-L1 expression and clinical benefits in anti-PD-1 therapy. Discussion: Preliminary observations showed that PD-L1 expression in immune cells is related to an immunosuppressive milieu in NSCLC and to clinical benefits of immunotherapy.