Abstract: Objective : To explore the feasibility and toxicity of preoperative neoadjuvant chemotherapy in the treatment of stage Ⅲ NSCLC and to evaluate its effects on tumor downstaging, resection rate and survival rate. Methods : From January 1990 to January 2002, 456 patients were randomly devided into group A (preoperative neoadjuvant chemotherapy group) and group B (control group,without neoadjuvant chemotherapy). Group A had 234 cases and group B had 222 cases. The patients in group A were gave 2 cycles of neoadjuvant chemotherapy, and operations were performed in 4 weeks after finishing the last chemotherapy. All 234 cases were gave intravenous chemotherapy. The regimens included Gem+DDP in 47 cases, NYB+DDP in 35 cases, MVP in 86 cases, and EP in 66 cases. The patients in group B were firstly operated. Results : The tumor response to induction chemotherapy was 67.95% (159/234) in group A. The tumor downstaging was 35.04% (82/234). The resection rate was 87.02% (181/208) in group A, and 83.78% (186/222) in group B. No significant differences of operative complications and mortality were observed between the group A and group B. The 1 -, 3- and 5-year survival rate were 76.07% 、52.99% and 34.18% in group A, and 69.82% 、41.44% and 22.97% in group B respectivelyK The long-term survival rate in group A was remarkably higher than that in group B (P<0.01). conclusion : The preoperative neoadjuvant chemotherapy is safe and effective. It is helpful to decrease the tumor staging, to increase the resection rate of the tumor, and to improve the long-term survival rate and life qualities of patients with stage Ⅲ NSCLC.