Background: The role of adjuvant CT for 4-5 cm primary lung tumors without any regional lymph node involvement following surgical resection is somewhat controversial. While it is favored in most cases, it should be individualized depending on other pathological risk factors and the patient's performance status. In this study, we investigated the benefit of adjuvant CT in elderly patients with 4-5 cm tumor size following complete surgical resection. Methods: We utilized Surveillance, Epidemiology, and End Results Program (SEER) database to identify elderly patients (≥65 years) with 4 to 5 cm sized non-small cell lung cancer after complete surgical resection diagnosed from 2010-2015. The baseline characteristics among the patients who received and didn’t receive adjuvant CT were compared using relevant parametric/non-parametric tests. Kaplan Meir curve was generated for the univariate survival analysis, and the log-rank test was used for comparison. Multivariate survival analysis was done using the cox proportional hazards regression model. Results: The database included 2582 patients. Among them, 492 (19.1%) cases had received adjuvant chemotherapy while 2090 (80.9%) cases had not. The population that received chemotherapy was younger than those that did not (Median:75 years vs 71 years, p < 0.001). The 5-year overall survival for patients who received chemotherapy was significantly higher than those who did not (53.9% vs 46.5%, P = 0.002). On the multivariate analysis adjusted for age, gender, race, income status, and type of surgery, cases with adjuvant chemotherapy had lower hazards as compared to those who had not received adjuvant chemo (Hazard Ratio (HR):0.86, confidence interval (CI): [0.75,0.99], P value = 0.04). Conclusions: Our study demonstrated a survival benefit with adjuvant CT for node-negative NSCLC of 4-5 cm size in the elderly population.