The chemical structure and physicochemical properties of eight mucopolysaccharides-glycosaminoglycans isolated from different types of connective tissue have been described. Special attention has been paid to the structure of polysaccharideprotein complexes and to the interactions of proteoglycans with collagen. The indirect effect of mucopolysaccharides on meat tenderness has been pointed out as involving the participation of these saccharides in collagen crosslinking. In addition the metabolism of mucopolysaccharides, their physiological functions, and their different applications have been described.