The treatment for stage III non-small cell lung cancer (NSCLC) often involves multi-modality treatment. This retrospective study aimed to evaluate whether multidisciplinary team (MDT) discussion results in better patient survival. MDT discussion was optional before February 2016 and was actively encouraged by the MDT committee beginning February 2016. We reviewed the medical charts and computer records of patients with stage III NSCLC between January 2013 and December 2018. A total of 515 patients were included. The median survival of all the patients was 33.9 months (M). The median survival of patients who were treated after MDT discussion was 41.2 M and that of patients treated without MDT discussion was 25.7 M (p = 0.018). The median survival of patients treated before February 2016 was 25.7 M and that of patients treated after February 2016 was 33.9 M (p = 0.003). The median survival of patients with stage IIIA tumors and those with stage IIIB tumors was 39.4 M and 25.7 M, respectively (p = 0.141). Multivariate analysis showed that MDT or not (p<0.001), T staging (p = 0.009), performance status (p<0.001), and surgery (p = 0.016) to be significant prognostic factors. The results of the study show that MDT discussion results in survival benefit in patients with stage III NSCLC. The MDT discussion, performance status, and if surgery was performed were independent prognostic factors for patients with stage III NSCLC.