Abstract: Objective:To investigate the clinical significance of epithelial-to-mesenchymal (EMT) in lung squamous cell carcino-ma (LSCC) and to examine the effect of EMT on the invasive and migration abilities of LSCC. Methods:Immunohistochemical stain-ing was performed to determine the expression of E-cadherin, Vimentin, and TGF- β 1 in 79LSCC patients, and the clinical significance was explored. SK- MES-1 lung squamous carcinoma cells were cultured in conditioned medium containing various concentrations of transforming growth factor-β 1 (TGF- β 1) for 5 and 10days. The expression levels of E-cadherin and Vimentin were detected via West-ern blot and reverse transcription-polymerase chain reaction (RT-PCR). With different concentrations and induction times, invasion and wound healing assays were performed to evaluate the invasion and migration abilities. Results:E-cadherin expression was significantly lower, whereas Vimentin expression was significantly higher in LSCC with lymph node metastasis than in that without noda metastasis (P <0.05). In the tissues of 79LSCC patients, TGF- β 1 expression was significantly related to lymph node metastasis ( P <0.05). Western blot showed that Vimentin expression was higher, whereas E-cadherin expression was lower in TGF-β 1 inducing medium with 10ng/mL SK-MES- 1 cells than in the other media. RT-PCR showed similar results. Scratch test and invasion assay both showed that treat -ment of cells with cytokines markedly enhanced the migration and invasion of the cells. Conclusion:Lymph node metastasis of LSCC correlates with EMT. SK-MES- 1 cells undergo EMT via TGF- β 1 induction, which enhances invasion and migration.