In recent years, the potential of several immune checkpoint (ICP) inhibitors in small cell lung cancer (SCLC) has been increasingly investigated. Despite the fact that in some trials the benefit of the addition of ICP inhibitors was only modest, results of the CheckMate-032 and Keynote-028 and 158 have led to the FDA approval of nivolumab and pembrolizumab as third-line treatment options for patients with extensive disease (ED)-SCLC. More recently, results of IMpower 133 formed the basis for the EMA approval of atezolizumab in combination with chemotherapy as a first-line treatment option for ED-SCLC. In addition, several ongoing first-line trials in ED-SCLC patients will report their results in the near future. Also in limited disease (LD) SCLC patients, several trials are examining the interactive effects of concurrent tumour irradiation with chemo- and immunotherapy. Until now, unfortunately, there are no validated biomarkers to identify those SCLC patients who might derive the best long-term survival benefit from chemo-immunotherapy.