Stage III non-small-cell lung cancer (NSCLC) with N2 lymph node involvement is a heterogeneous group with different potential therapeutic approaches. Patients with potentially resectable III-N2 NSCLC are those who are considered to be able to receive a multimodality treatment that includes tumour resection after neoadjuvant therapy. Current treatment for these patients is based on neoadjuvant chemotherapy +/- radiotherapy followed by surgery and subsequent assessment for adjuvant chemotherapy and/or radiotherapy. In addition, some selected III-N2 patients could receive upfront surgery or pathologic N2 incidental involvement can be found during analysis of the surgical specimen. The standard treatment for these patients is adjuvant chemotherapy and evaluation for complementary radiotherapy. Despite being a locally advanced stage, the cure rate for these patients continues to be low, with a broad improvement margin. The most immediate hope for improving survival data and curing these patients relies on integrating immunotherapy into perioperative treatment. Immunotherapy based on anti-PD1/PD-L1 immune checkpoint inhibitors is already a standard treatment in stage III unresectable and advanced NSCLC. Data from the first phase II studies in monotherapy neoadjuvant therapy and, in particular, in combination with chemotherapy, are highly promising, with impressive improved and complete pathological response rates. Despite the lack of confirmatory data from phase III trials and long-term survival data, and in spite of various unresolved questions, immunotherapy will soon be incorporated into the armamentarium for treating stage III-N2 NSCLC. In this article, we review all therapeutic approaches to stage III-N2 NSCLC, analysing both completed and ongoing studies that evaluate the addition of immunotherapy with or without chemotherapy and/or radiotherapy.