Lectins are structurally and functionally diverse group of proteins or protein domains capable of specific binding of oligosaccharide structures present on cell surfaces, the extracellular matrix, and secreted glycoproteins. Animals lectins are classified into six groups: C-type lectins, S-type lectins (galectins), I-type lectins, P-type lectins, pentraxins, and others. In this review, the basic knowledge regarding structure and function of animal lectins is presented.