Immune checkpoint inhibitors have changed the history of NSCLC treatment by becoming, alone or in combination with platinum-based chemotherapy, a mainstay of first-line therapy for advanced NSCLC. This increasingly dictates the identification of predictive biomarkers of response that can guide patient selection, in order to rationalize and personalize therapies, particularly in elderly patients. Immunotherapy in these patients raises questions of efficacy and tolerability related to aging, which is accompanied by a progressive decline in various body functions. Physical, biological and psychological changes contribute to individual validity status and, preferably, ‘fit’ patients are generally enrolled in clinical trials. In elderly patients, especially frail and complex patients with more than one chronic disease, data are poor and specific prospective studies are needed. This review reports the main available results on the use of immune checkpoint inhibitors in older patients with advanced NSCLC, in terms of efficacy and toxicity, and aims to highlight the need to better predict which patients might benefit from immunotherapy agents by probing knowledge and integrating information on immune system changes and age-related physiopathological modifications.