Patients who receive radiation therapy for non-small cell lung cancer (NSCLC) will require accurate targeting of the grossly involved primary and nodal disease. However, the treatment of grossly uninvolved elective nodal sites that may harbor microscopic occult disease is controversial. In simple terms, physicians are guided by 1 of 2 paradigms when they decide about the use of elective nodal irradiation in NSCLC. First, one may consider that high doses of radiation therapy for the primary and grossly involved lymph nodes represents the most important aspect of treatment and that elective irradiation of potential occult micrometastasis is not necessary because it may limit the doses that can be given to the gross disease. Additionally, this line of thought often includes the belief that most or all patients with occult micrometastasis are not curable. Alternatively, one may consider that the evidence for a dose response, for grossly involved NSCLC, beyond 60 Gy is very limited and that the omission of elective nodal irradiation obviates the chance for cure in many patients. These small deposits of tumor in regional nodes are common, are amenable to low doses of radiation (50 Gy), and treatment of these lesions does result in cures. This review focuses on this latter paradigm and the available evidence to support it. Copyright (C) 2000 by W.B. Saunders Company.