Abstract: Objective To investigate the role of an inhibitor of guanine nucleotided dissociation for Rho proteins (LyGDI ) in human lung cancer and to evaluate its clinical significance. Methods The differentical protein expression of LyGDI among lung cancer and its corresponding normal lung tissue and lung tissue was analyzed with western blotting hybridization and immunohistochemistry stain by using well characterized monoclonal antibodies. Results The results of western blotting suggested that the expression of LyGDI polycloral was significantly up-regulated in lung cancer compared with the corresponding normal lung issue and lung tissue in 35cases (P<0.05), but it wasn't significantly up-regulated in 11 cases. It was not associated with SCLC and NSCLC differentiation of lung cancer. In NSCLC, the expression of LyGDI did not seem to vary between the squamous carcinoma and adenocarcinoma, but it was associated with lymph node metasis . Conclusion The up-regulation of LyGDI is marked correlated with the metasis and histology of lung cancer, but not with clinical and pathological types. LyGDI may play a role in lung cancer.