Objective To evaluate the local failure and the impact on survival by prospectively comparing involved field radiotherapy (IFRT) and elective nodal irradiation (ENI) in combination with concurrent chemotherapy for locally advanced non-small cell lung cancer (LA-NSCLC). Methods LA-NSCLC patients were treated with 2 cycles of carboplatin (AUC=5－6, d1) combined with paclitaxel (175 mg/m²), followed assessment without distant metastasis, then randomized into IFRT (45 patients) or ENI (54 patients) arm. IFRT included primary tumor, ipsilateral hilar and positive mediastinal lymph nodes;ENI included the primary lesion, ipsilateral hilar, bilateral mediastinal lymph node drainage and bilateral supraclavicular area. The prescription dose was given as high as possible with V₂₀≤35% and spinal cord dose ≤50 Gy, combined weekly paclitaxel 40 mg/m² concurrent chemotherapy. The Kaplan-Meier method was used to estimate survival data and the log-rank method was used to test distribution of survival time between arms. Results The follow-up rate was 99%. 49,29 and 17 patients were followed-up for 1-,2-and 3-year, respectively. More patients from group IFRT received>60 Gy than ENI (49% vs. 26%,χ²=5.59,P=0.018). The local failure rates were 29% and 36%, respectively (χ²=0.46,P=0.497).The 1-, 2-and 3-year local tumor progression-free survival rates were 76%, 69%, 65% and 80%, 53%, 49%(χ²=0.74,P=0.389), respectively;the 1-, 3-and 5-year overall survival rates were 80%, 41%, 33% and 69%, 32%, 13%(χ²=3.97,P=0.046), respectively. There were no significant differences in acute and
 late toxicities between the arms (χ²=3.910－0.155,P=0.142－0.925). Conclusions IFRT improved radiation dose and survival rate and did not increase the failure of elective lymph node region compared with ENI. The toxicities were no differences between IFRT and ENI. Further investigation with big size sample is warranted.