Before the introduction of targeted therapy and immunotherapy, patients with metastatic non-small-cell lung cancer (NSCLC) had a 5-year overall survival (OS) rate of up to 10%. After the positive results of KEYNOTE-024, pembrolizumab was approved in a first-line setting for patients with metastatic NSCLC and PD-L1 ≥ 50%. A small number of patients had a durable response to immunotherapy, and so far it has not been discovered who will benefit. The aim of this study was to investigate the efficacy of first-line pembrolizumab in patients with locally advanced and metastatic NSCLC with high PD-L1 expression in a real-world setting. We enrolled 35 patients with locally advanced and metastatic NSCLC who had PD-L1 ≥ 50%. Progression-free survival was 9 months, 95% CI (2.6-15.4). Overall survival was 14 months, 95% CI (0-28.5). Five-year OS rate for the whole group of patients was 20%, and the six-year OS rate was 17.2%. Immunotherapy was a revolution in the treatment of NSCLC. We still do not know which patients will benefit from immunotherapy, but patients who do respond may experience long-term outcomes.