In locally advanced non-small cell lung cancer (NSCLC) patients, consolidation therapy with durvalumab (an anti-PD-L1 monoclonal antibody) has proven to significantly increase both progression free and overall survival after chemoradiotherapy. Here, we describe a case of acute pneumonitis during durvalumab administration for locally advanced NSCLC, causing persistent symptomatology and steroid treatment to date. To our knowledge, acute-onset pneumonitis during infusion of a PD-L1 inhibitor has not been described previously. This case illustrates that ICI-induced pneumonitis can occur anytime during treatment, especially after chemoradiation.