Objective To investigate the efficacy of implantation of radioactive iodine-125 (125I) seeds combined with chemotherapy in treatment of stage Ⅲb and Ⅳ non-small cell lung cancer (NSCLC).Methods Ninety patients with stage Ⅲb and Ⅳ NSCLC were divided into two groups.The combined group (n=43) received chemotherapy with TP (paclitaxe plus cispla tin) or GP (gemcitabine plus cisplatin) 3 days after 125I particles implantation,and the control group (n=47) only received TP or GP chemotherapy.The effective rate,1-year and 2-year survival rate,the median survival time were compared between the 2 groups.Results The total effective rates of the combined group and the control group of stage Ⅲ b NSCLC were 84.00％ and 48.28％,and the effective rates of stage Ⅵ NSCLC were 72.22％ and 33.33％ (both P＜0.05).The 1-year and 2-year survival rate of the combined group and control group of stage Ⅲb NSCLC were 67.80％,36.00％ and 37.90％,13.83％,respectively (both P＜0.05).The median survival time was 15.7 months and 8.6 months.However,the survival rates of the combined group and the control group of stage Ⅳ NSCLC were 44.44％,16.70％ and 22.22％,11.10％,respectively,while the difference was not statistically significant (P＞0.05).The median survival time was 8.9 and 6.0 months.Conclusion The implantation of radioactive 125I seeds combined with chemotherapy can obtain a significant efficacy in the treatment of stage Ⅲb and stage Ⅳ NSCLC.For patients with stage Ⅲb NSCLC,combined therapy can improve the survival rate.