Objective To evaluate clinical factors as predictors of radiation pneumonitis(RP)in advanced stage non-small cell lung cancer(NSCLC)patients treated with concurrent radiochemotherapy when gross tumor volume is 70 Gy. Methods Data of 84 patients with histologically proved NSCLC treated with 3DCRT or IMRT were collected. To evaluate the correlation between clinical parameters and radiation pneumonitis(RP). The clinical parameters were considered: pathological type, therapy agents, age,gender, stage, karnofsky performance status(KPS), smoking status, diabetes, chronic obstructive pulmonary disease(COPD). Results The occurrence of grade 1,2 RP was 63%, 33%, respectively. In univariate analysis, diabetes was significantly associated with RP of ≥ grade 1(x2 =4.03, P = 0.045)and ≥grade 2(x2 = 15.59 ,P =0.000). KPS was significantly associated with RP of ≥grade 1(x2 =3.98 ,P = 0.046)and ≥grade 2(x2 = 5.21, P = 0.023). In logistic multivariate analysis, diabetes was significantly associated with RP of ≥grade 1(x2 =5.50,P =0.019)and ≥grade 2(x2 = 12.92,P =0.000). KPS was significantly associated with RP of ≥ grade 1(x2 = 6.29, P = 0.012)and ≥ grade 2(x2 = 6.61, P =0.010). Conclusion The definite statistical significant risk factors of RP are diabetes and KPS.