Galectins are a family of lectins characterized by an affinity for β-galactosides through the carbohydrate recognition domain (CRD). The extracellular and intracellular presence of Galectins has been described. Their activity and functions are mainly attributed to cell type. The tumor microenviroment is a complex milieu connected with immunosupression, angiogenesis and hypoxic compartments. The studies of interactions between Glycans-Lectins are highly advanced and promising. We are not able to explain the pathogenesis of many diseases only by protein-protein interactions, that is why in these studies is a chance to find a new therapeutic targets. Galectins play a fundametal functions in tumor growth and progression, angiogenesis, adhesion, tumor immune-escape. They are also active in inflammation, fibrosis, organogenesis and immunological functions. The most known Galectin is Gal-3. Depending on the localization Gal-3 may exhibit either pro-apoptotic or anti-apoptotic activity. This publication presents role of Galectins in hematological malignancies and shows potencial prognostoic value and new therapeutic possibilities.