The Galectin family of proteins, with specificity for Nacetyllactosamine containing glycoproteins, consists of beta-galactoside binding lectins containing homologous carbohydrate recognition domains (CRDs).They also possess hemagglutination activity, which is attributable to their bivalent carbohydrate binding properties. Galectins are active both intracellularly and extracellularly. Although they are localized primarily in the cytoplasm and lack a classical signal peptide; they can be secreted by one or more as yet unidentified non-classical secretory pathways. They have diverse effects on many cellular functions including adhesion, migration, polarity, chemotaxis, proliferation, apoptosis, and differentiation. Galectins may play a key role in many pathological states, including autoimmune diseases, allergic reactions, inflammation, tumor cell metastasis, atherosclerosis, and diabetic complications.