Abstract: Objective To explore the effect of the combined sequential application of er-lotinib between the chemotherapy periods on the treatment of the patients with advanced non small cell lung cancer (NSCLC).Methods 45 patients with advanced NSCLC were collected.The pa-tients with the initial treatment were treated with gemcitabine combined with platinum for chemotherapy,while the patients with retreatment were treated with docetaxel or pemetrexed for chemotherapy.Between the chemotherapy periods,the sequential erlotinib therapy was applied to all the patients.The short-term efficacy and the adverse reactions were evaluated and compared. Results The clinical efficacy of the initial treatment patients and the retreatment patients were 27.6% and 18.8% respectively (P >0.05),and the clinical control rate of the initial treatment patients was significantly higher than that of the retreatment patients (P <0.05).The clinical ef-ficacy of the patients with a history of smoking was significantly lower than that of the patients without a history of smoking (P <0.05).The clinical efficacy of the initial treatment patients with age over 65 years old was significantly higher than that of the initial treatment patients with age less than 65 years old(P <0.05).The clinical efficacy of the initial treatment patients with stage Ⅲ b was significantly higher than that of the initial treatment patients with stage Ⅳ (P <0.05).The clinical efficacy of the retreatment patients with adenocarcinoma pathological type was significantly higher than that of the patients without adenocarcinoma pathological type (P <0 .0 5 ).The main adverse reactions were nausea ,diarrhea ,rash ,vomiting and loss of appetite . Conclusion The clinical efficacy of the combined sequential application of erlotinib between the chemotherapy periods in the treatment of the patients with advanced NSCLC is not such high. Smoking history,age,tumor stage and pathological type may affect its curative effect.Efficacy of this therapy in controlling the disease progress of the initial treatment patients is significant,the adverse reactions are mild,and the tolerance of the patients for the therapy is higher.