In the treatment of limited-stage small cell lung cancer (LD-SCLC) and unresectable locally-advanced non-small cell lung cancer, several phase III trials and meta-analysis have demonstrated the following: 1) combining chemotherapy and thoracic irradiation is better than chemotherapy alone or radiotherapy alone, 2) the concurrent use of chemoradiotherapy has been expected a better survival than the sequential use, 3) the improvement in outcome seen with a concurrent chemoradiotherapy approach may be because of spatial cooperation, enhanced radiosensitization, and/or enhanced cytotoxicity, and 4) the chemoradiotherapy is tolerable without significant morbidities, such as pneumonitis and esophagitis. However, the chemoradiotherapy is still an investigational strategy because of the absence of a definite schedule and dose on radiotherapy. Newer, more tolerable chemotherapeutic agents, molecular biologic novel approaches and newer irradiated procedures are now being investigated.