According to the 8th TNM classification, stage III non-small-cell lung cancer (NSCLC) should be subdivided into stage IIIA which represents a heterogeneous group, and stages IIIB and IIIC. N2 involvement defines the most common stage IIIIA subgroup but also the most diverse subcategory.Regarding stage IIIA, an intervention may be considered for T3N1 and T4N0-1 tumours when a complete resection may be obtained, in some cases after induction therapy or followed by adjuvant therapy. Treatment of N2 involvement remains more controversial. When N2 disease is discovered incidentally during thoracotomy a resection should be performed if this can be complete. Most patients with N2 disease proven by a minimally invasive or invasive technique are treated with induction therapy followed by surgery or radiotherapy. Lobectomy may be recommended in those patients with proven mediastinal downstaging after induction therapy. Patients with bulky N2 disease are mostly treated with combined chemoradiotherapy followed by immunotherapy. Immunotherapy has profoundly changed the therapeutic approach for metastatic lung cancer. Recent randomised trials have shown that immunotherapy is also an effective treatment for locally advanced stage III lung cancers, but its exact position in therapeutic algorithms including radiotherapy and/or surgery still remains to be determined.The extreme variability of stage III is at the origin of controversies that have lasted for more than 30 years. Nevertheless, the consensus requires a joint and comprehensive evaluation of the locoregional disease as well as the patient in his globality. Every patient should be discussed in a multidisciplinary team.1877-1203/© 2022 SPLF. Published by Elsevier Masson SAS. All rights reserved.