The utility of adjuvant chemotherapy (AC) after neoadjuvant therapy and curative intent surgery for clinical stage IIIA (cIIIA) non-small cell lung cancer (NSCLC) is not defined. We sought to evaluate the contribution of AC to overall survival (OS) in patients with cIIIA NSCLC who underwent neoadjuvant therapy followed by curative intent surgical resection. The National Cancer Database was queried from 2010 to 2016 for patients with cIIIA NSCLC who underwent curative intent surgical resection after neoadjuvant therapy. Patients were grouped by receipt of AC, and OS was calculated using the Kaplan-Meier method. The association between mortality and AC was evaluated using Cox regression. Ninety-day landmark and propensity score-matched analyses were performed to address bias associated with early postoperative morbidity and mortality. Of 3847 patients who met the inclusion criteria, 780 received AC (20.2%). In the unadjusted cohort there was no difference in 5-year OS between the AC and no AC groups (42.8% vs 43.9%, P = .105). Cox regression demonstrated a decreased risk of mortality in pN > 0 patients receiving AC (hazard ratio, 0.79; 95% confidence interval, 0.68-0.92; P < .003), whereas no difference was seen in node-negative patients (hazard ratio, 0.95; 95% confidence interval, 0.78-1.17; P = .64). In the propensity score-matched groups OS was significantly increased in pN > 0 patients who received AC (5-year OS: 42.4% vs 37%, P < .01), whereas no survival benefit was seen in those who were pN0. For patients with completely resected cIIIA NSCLC after neoadjuvant therapy, AC is associated with an increase in OS for patients with residual pathologic lymph node involvement.