Abstract: Objective: : To investigate the correlation between the expression of thyroid transcription factor-1(TTF-1)and apoptosis and angiogenesis in lung cancer. Methods : A paraffin tissue microarray containing 829 tissuecores including 196 lung carcinomas, 10 normal lung tissues and 1 muscular tissue was constructed. Terminaldeoxynucleotidyl transferase dUTP nick end labeling(TUNEL) and immunohistochemical staining were usedto detect apoptosis and the expression of TTF-1 and CD34 in different types of lung carcinomas. A LeicaQ500 MC image analysis system was employed to measure and calculate TTF-1 Positive Units (PU), Apoptotic Index(AI), and Microvessel Density(MVD). Results : AI of small cell lung cancer and large cell lung cancerwas lower than that of adenocarcinoma and squamous cell carcinoma of the lung(P=0.000). AI of lung carcinomas with lymph node metastases was lower than that of those without lymph node metastases(P=0.039). AIof lung carcinoma in TNM stage Ⅱ-Ⅳ was lower than that in stage Ⅰ(P=0.008). TTF-1 PU was negatively correlated with AI in small cell lung cancer(r=-0.752,P=0.000). MVD of lung carcinomas without lymph nodemetastases was lower than that of those without lymph node metastases(P=0.031). MVD of lung carcinomasin TNM stage Ⅰ was lower than that in stage Ⅱ-Ⅳ(P=0.040). TTF-1 PU was positively correlated with MVDin lung adenocarcinoma(r=0.708,P=0.000). Conclusion : There is a negative correlation between TTF-1 PUand AI in small cell lung cancer. TTF-1 PU was positively correlated with MVD in lung adenocarcinoma. TTF-1may contribute to the development of lung adenocarcinoma by inducing tumor angiogenesis.