Immune checkpoint inhibitors are effective in restoring the T-cell mediated immune response and can achieve a deep and durable response in a small subset of cancer patients. As only 15% to 25% of the patients with advanced NSCLC will benefit from immunotherapy, a predictive biomarker is required to select patients who will potentially respond. To date, the most intensively studied potential biomarkers consist of the programmed death ligand 1 (PD-L1) expression, the tumour mutational burden (TMB) and the tumour micro-environment (TME), each with its own advantages and challenges. This article will briefly describe each of these biomarkers and will touch upon the relationship between certain genetic modifiers and a response to immunotherapy.