Abstract: Objective: To evaluate the effects of Navelbine and Cisplatin combined with Megestrol Acetate on pa-tients with stage IIIa and IV non-small cell lung cancer (NSCLC). Methods: A total of 75 patients with advanced NSCLCwere randomly divided into two groups: the trial group (Navelbine and Cisplatin combined with Megestrol Acetate) and thecontrol group (Navelbine and Cisplatin). The chemotherapy was repeated every 21 days, and the effects were analyzed andcompared after two cycles were finished. Results: The response rates were 43.59%(17/39) in the trial group and 41.69%(15/36) in the control group. The median survival time was 9.1 months in the trial group and 8.9 months in the controlgroup. The median TTP was 4 months in the trial group and 3.6 months in the control group. The 1-year survival rate was38.5% in the trial group and 38.9% in the control group, without significant difference (P>0.05). The major adverse reac-tions were stage 3 to stage 4 myelosuppression, nausea and vomiting. The incidence of leucopenia, anemia and thrombo-cytopenia was 7.69%, 0% and 7.69% in the trial group and 25.00%, 17.44%, and 13.89% in the control group, respec-tively(P<0.05). Improvement in quality of life was greater in the trial group than in the control group(P<0.05). Conclusion: Megestrol Acetate can effectively improve the efficacy of the chemotherapy regimen with Navelbine and Cisplatin in pa-tients with advanced NSCLC. And without causing significant side effects, Megestrol Acetate can improve the quality oflife of patients with advanced NSCLC.