Galectin-3, a multifunctional beta-galactocide binding lectin possibly participates in a variety of biological events including cell proliferation, differentiation, and apoptosis. The implication of galectin-3 during malignancy progression has been suggested in several cancers, including colon, prostate, thyroid, and breast cancer, however, scarce data are available in gastric cancer. We examined the expression of galectin-3 in 86 primary gastric cancers and the 40 metastatic lymph nodes by immunohistochemistry to explore whether it is related to the malignant progression. Positive galectin-3 expression was observed in 84% of the gastric cancer cases. In enhanced cells of cancerous lesions, 48% showed stronger nuclear immunoreactivity than cytoplasmic one, whereas adjacent epithelial cells showed little or weak nuclear immunoreactivity. When galectin-3 expression in gastric carcinoma was compared with that in gastric tissues adjacent to the cancers, there was a significant difference. The degree of enhancement of immunoreactivity was different corresponding to various histopathological subtypes in cancer tissues. A significantly stronger expression of galectin-3 in cancer tissues was only observed in papillary and poorly differentiated adenocarcinoma. When galectin-3 expression and tumor progression (TNM staging) was compared, a significant correlation was observed in overall cases, and only in poorly differentiated adenocarcinoma the galectin-3 expression correlated with tumor progression among various subtypes. Galectin-3 expression was observed significantly stronger in metastatic lymph nodes than in the primary gastric cancers, and also in these cases among histological subtypes, only in poorly differentiated adenocarcinoma, the expression of galectin-3 in metastatic lymph nodes was stronger than the primary cancer. In conclusion galectin-3 might be a useful tumor marker for gastric cancers with respects to tumor progression and potentiality of lymph node metastasis especially in certain histological types of gastric cancer.