Background: We investigated case reports of nivolumab-induced ILD in patients with non-small cell lung cancer to identify risk factors for poor prognosis of ILD. Methods: Among data obtained during post-marketing surveillance of nivolumab, case reports of ILD with detailed clinical course and chest imaging (CT) findings were assessed by the ILD Expert Review Committee, which consists of respiratory medicine specialists and expert chest radiologists. The imaging findings were examined and classified into those with typical or atypical patterns. Atypical patterns included shadows limited to surrounding tumors designated as “peritumoral infiltration”, relapse of radiation pneumonitis, worsening of underlying infection, and predominant shadow in diseased side. CT pattern was classified as DAD (diffuse alveolar damage) or non-DAD. Data were analyzed using a multivariate stepwise logistic regression analysis. Results: Among 160 reported cases of ILD, 140 cases were considered to be induced by nivolumab. Imaging findings showed typical patterns in 92 patients, and 23 (25.0%) died of ILD. Atypical patterns were noted in 48 patients, and 5 (10.4%) died of ILD. The following table summarizes the results of univariate and multivariate analyses of risk factors for poor prognosis of ILD. See table. DAD pattern was observed in 20, 14 (70%) among them showed fatal outcome, whereas non-DAD pattern showed it in 14/120 (11.7%). Male and pretreatment CRP level were significant risk factors for fatal outcome. Conclusions: Nivolumab-induced ILD may show some atypical pattern that was not seen in conventional chemotherapy or EGFR-TKI. Outcome of patients with atypical patterns was better than those with typical patterns. DAD pattern at CT, male, and pretreatment level of CRP were identified as risk factors of fatal outcome.