Multi-functional galecin-3 is found in the nucleus as well as in the cytoplasm. In order to clarify the role of galectin-3 in progression of lung tumors we here immunohistochemically investigated levels in 300 non-small cell lung cancers (NSCLCs), 164 adenocarcinomas (ACs) and 136 squamous cell carcinomas (SCCs), using a monoclonal antibody, Galectin-3 was found to be overexpressed in the nucleus in 87 (53.0%) and 39 (28.7%) of the ACs and SCCs, respectively, and in the cytoplasm in 57 (34.8%) vs 27 (19.9%)(p= 0.004, p< 0.001). In ACs, nuclear overexpression inversely correlated with lymph node-metastasis (p= 0.049) in association with tendency of cytoplasmic overexpression to progression of clinical stage and linkage to histological malignant grading in ACs. In SCCs no correlation was found between galectin-3 positivity and clinicopathological variables. There was no link in either case with survival duration examined by the Kaplan-Meier method. In conclusion, it seems likely that galectin-3 plays opposite roles in the cytoplasm and nucleus and that down-regulation in latter may be involved in cancer progression in lung adenocarcinoma cases.