Radiotherapy is a major therapeutic in non small-cell lung cancer. The development of three-dimensional conformal radiotherapy in the 90' authorized dose escalation to occur, and concomitant association with chemotherapy to be delivered with acceptable toxicities. Multimodal therapeutic sequences are now investigated integrating new techniques of irradiation: intensity modulation allows an even superior dose escalation and an increased focalisation of the ballistics; stereotactic radiotherapy and proton-beam radiotherapy, less available in Europe at the time, would be indicated in the exclusive treatment of early-stage tumors in non-operable patients. These improvements made possible sequential and concurrent association of radiotherapy with new-generation chemotherapy regimens, such as gemcitabine, requiring dose adaptation but improving systemic tumor control. Regarding the optimization of chemoradiation, there is a need to reevaluate our knowledge in the treatment of locally advanced non small-cell lung cancer, by launching multimodal therapeutic strategies, including radiotherapy, chemotherapy and surgery. These developments make radiotherapy one of the most promising therapeutics in thoracic oncology.