Abstract: Objective To analyze the TTF-1 expression in patients with advanced non-small cell lung cancer and its prognostic significance. Methods Clinicopathological data were collected from patients with advanced non-small cell lung cancer who underwent TTF-1 in our hospital from June 2008 to June 2011.Relation of TTF-1 expression with clinicopathological features and prognosis of patients with advanced non-small cell lung cancer was studied. Results The TTF-1 expression level and histological classification were significantly higher in 67 patients with squamous cell carcinoma and adenocarcinoma（P＜0.05）.However,no significant difference was observed in gender,age,smoking,TNM staging and histological classification,as well as in overall survival time of patients with positive or negative TTF-1 expression（median survival time 27.5 months vs 29.2 months,P＞0.05）. Conclusion TTF-1 can be used in differential diagnosis of squamous cell carcinoma from adenocarcinoma,but TTF-1 expression may not be related with the prognosis of patients with advanced non-small cell lung cancer.