Abstract: Objective To explore the expression of metastasis suppressor 1（MTSS1）in the development and progression of non-small cell lung cancer （NSCLC）and its clinical significance. Methods The paraffin-embedded tissues from 98 patients with NSCLC were collected from March 2006 to March 2008 in our hospital to construct tissue microarrays. The immunohistochemistry was used to measure the expression of MTSS1 in 98 tissues of NSCLC and paired corresponding normal adjacent tissues. The relationships between the expression of MTSS1 and clinicopathological characteristics （age，gender，lymph node metastasis，histological type，degree of differentiation and TNM stage） were analyzed. The overall survival of different expression patterns of MTSS1 was followed up. The pcDNA3.1-MTSS1 expression vector （pcDNA3.1-MTSS1 group） and pcDNA3.1 empty vector （pcDNA3.1 group） were constructed to transfect the A549 cells. Western blotting was used to analyze the protein levels of MTSS1 in both groups. The proliferation and migration of A549 cells were investigated by tetrazolium salt MTT and scratch test. Results The MTSS1 postive-expression rate of cancer tissue was higher than that of adjacent tissue （56.1％ vs. 100.0％， P＜0.05）. The MTSS1 expression was correlated with lymph node metastasis and TNM stage （P＜0.05）， rather than gender， age， degree of differentiation and pathological types. The median overall survival of MTSS1 positive expressers was 40.9 months， higher than 21.5 months of negative expressers with statistically significant （P＜0.05）. Multivariate analysis showed that MTSS1 was an independent factor affecting the prognosis of patients with NSCLC. There were a higher level of MTSS1 and lower proliferation and migration ratios in pcDNA3.1-MTSS1 group versus pcDNA3.1 group （P＜0.05）. ConclusionMTSS1 was widely lost in the development and progression of NSCLC and overexpression of MTSS1 can rescue the inhibition of cell growth， indicating that MTSS1 might modulate the development and progression of NSCLC.