Abstract: Objective To compare toxicities and clinical outcomes of involved field irradiation (IFI)and with elective nodal irradiation (ENI)intensity modulated radiation therapy (IMRT)with concurrent chemotherapy for locally advanced non-small cell lung cancer (LA-NSCLC). Methods 49 patients with of LA-NSCLC were prospectively randomized into IFI group and ENI group，receiving 2 cycles of concurrent chemotherapy and radical IMRT. Results ≥grade 2 radiation pneumonitis developed in 8.0% of the patients in IFI group and 37.5% in ENI group (P=0.01).The mean prescription doses to grass tumor volumes with IFI and ENI were (66.2±6.5)Gy and (61.3±6.3)Gy (P=0.01).The responsive rates were 92.0% and 66.7% (P=0.03)，and the elective nodal failure (ENF)rates were 4.2%and 4.0% (P=0.49)，respectively.The 1-year local-failure rates were 8.0% and 16.7% (P=0.62)，while the 1-year survival rates were72.0% and 62.5% (P=0.48)，respectively. Conclusion IFI IMRT with concurrent chemotherapy for LA-NSCLC could reduce the probability of normal tissue complications and improve the target dose and tumor control rate without increasing incidence of elective nodal failure.It might further prolong patients' survival.