Japan has the highest percentage of elderly population in the world; consequently, Japan has an aging society that is not observed in other countries. Lung cancer is the leading cause of cancer deaths in Japan. Consequently, it has become increasingly important to establish an effective treatment regimen for elderly patients with advanced non-small-cell lung cancer (NSCLC). Standard first-line chemotherapy for younger patients with stage IV NSCLC includes platinum-combination therapy. However, two standard options are available for elderly patients with advanced NSCLC. The first is single agent chemotherapy, and the second is doublet chemotherapy. Treatment options should be tailored for elderly patients based on the comprehensive evaluation and the evidence from clinical trials for. This article reviews the available data on radiation therapy and systemic chemotherapy for elderly patients with NSCLC, and assesses the role of comprehensive geriatric assessment (CGA) in the evaluation of elderly patients.