Abstract: Objective To investigate short-term and long-term efficacy and toxicity of intensitymodulated radiotherapy(IMRT) in combination with gemcitabine and carboplatin solution(GC) plus sequential chemotherapy and sequential chemoradiotherapy alone on locally advanced non-small cell lung cancer(NSCLC) patients. Methods We retrospectively analyzed 65 patients with locally advanced NSCLC who were not allowed and refused to receive operation. Thirty-two patients received IMRT with concurrent GC regimen and sequential chemotherapy, and 33 patients were treated with sequential chemoradiotherapy alone. Short-term and long-term efficacy and toxicity of two groups were compared by statistical analysis. Results All patients finished their course of treatment and the follow-up rate was 100%. The short-term response rate of IMRT combined with chemotherapy and sequential chemotherapy group was 75%, and the rate of sequential chemoradiotherapy alone group was 66.7% (P<0.05). The 1- and 3-year overall survival(OS) rates of the combination group were 68.2% and 20.5%, respectively, while those of sequential chemoradiotherapy alone group were 50.1% and 11.3%, respectively(P<0.05). No difference of toxicity between two group was observed (P>0.05). Conclusion It could increase the long-term survival rate of patients with locally advanced NSCLC by IMRT combined with GC and sequential chemotherapy and the toxicity of treatment could be tolerated.