The disaccharide repeating unit of Chondroitin sulphate consists of N-acetyl galactosamine sulphate linked β1,4 to glucuronic acid. Each monosaccharide may be left unsulphated, sulphated once, or sulphated twice. The most common pattern has the hydroxyls of the 4 and 6 positions of the N-acetyl-galactosamine sulphated, with some chains having the position 2 of the glucuronic acid sulphated.