Objective To analyze the management and outcome of symptomatic radiation-induced lung injury (SRILI) in non-small cell lung cancer (NSCLC).Methods Between 2000 and 2007,80 NSCLC patients, who developed SRILI with detailed record, were enrolled into the analysis. The classification of RILI was evaluated according to common terminology criteria for adverse events, version 3.0. Asame patient might be assigned into more than one grade of SRILI classification for analysis as he or she experienced more than one phase of RILI during the disease course.There were grade 2 (G₂), G₃, G₄ and G₅ SRILI, which were seen in 49, 46, 1 and 4 patients, respectively. Results Eighty-seven percent of patients with G₃SRILI and three patients with G₂ SRILI accompaniedwith fever were treated with corticosteroid. Some of them received prophylactic administration of first-line antibiotics. The initial dose of steroid ranged from 20 to 66.7 mg prednisone equivalent daily; the median effective dose was 33.3mg daily. The dose of steroid decreased by slow taper; the median duration of treatment was 33 days. Of the 34 patients who underwent steroid treatment and received evaluation of response to steroid treatment, 65% were steroid-sensitive, and 32% were steroid-dependent. Thirty-one percent of patients with G₂ SRILI progressed to G₃, and 9% of patients with G₃ SRILI upgraded to G₅.Conclusions Corticosteroid is the primary therapy for G₃ SRILI and may also be considered for G₂ SRILI accompanied with fever. Meanwhile, prophylactic administration of first-line antibiotics can be chosen. Steroid is effective in the treatment of SRILI, and SRILI related mortality is low with timely steroid treatment.