Background: Lung cancer is the leading cause of cancer related deaths. The median age of those diagnosed with lung cancer continues to increase as the overall population ages. Consolidation immunotherapy after chemoradiation has become the standard treatment for patients with unresectable stage III NSCLC. However, little has been reported regarding the safety and efficacy of this strategy in an elderly patient population. Methods: Data was analyzed from a randomized phase II clinical trial in patients with unresectable stage III non-small cell lung cancer (NSCLC) who were randomized to Nivolumab (N) or Nivolumab/Ipilimumab (NI) after concurrent chemoradiation. We performed an ad-hoc analysis comparing the efficacy and toxicity based on age groups <65 and ≥ 65. A total of 54 patients received N (480mg IV every 4 weeks for up to 6 cycles) and 51 patients received N (240mg IV every 2 weeks) + I (1mg/kg IV every 6 weeks for up to 4 cycles). Results: From 9/2017 to 4/2021, 105 patients were enrolled. Fifty-five were age <65 (26 in N and 29 in NI) and 50 were ≥65 (28 in N and 22 in NI). Patients were matched for baseline characteristics (Table). In the N alone group, pneumonitis was noted in 14 patients: 9 (34.6%) <65 and 5 (17.9%) age ≥ 65 (p=0.16). In the NI group, 19 patients experienced pneumonitis: 9 (31%) were<65 and 10 (45.5%) were ≥ 65 (p=0.29). Hospitalization was noted in 9 patients in the N group: 6 (23.1%) < 65 and 3 (10.7%) ≥ 65 (p=0.28). In the NI group, 20 patients were hospitalized: 9 (31%) were <65 and 11(50%) were ≥ 65 (p=0.16). At 24 months, the PS for all patients <65 was 61.3% and 60.5% for patients ≥65(p=0.62). PFS was 46.8% for <65 and 73.8% for ≥65 (p=0.15) in the N group and 75.4% for <65 and 45.4% for ≥65 in the NI group(p=0.02). OS for patients <65 was 84% at 24 months and 73% for ≥65 for both groups (p=0.466). For individual groups, OS was 72.5% in <65 and 81.4% for ≥65 (p=0.27) in the N group and 92.8% for <65 and 68.2% for ≥65 in the NI group (p=0.029). Conclusions: Adverse events in both age groups were comparable but overall higher in NI arm in both younger and elderly patients. OS estimates were similar for both age groups in N while higher in younger patients compared to older adults in NI.