Phosphorylases are useful catalysts for the practical preparation of various sugars. The number of known specificities was 13 in 2002 and is now 30. The drastic increase in available genome sequences has facilitated the discovery of novel activities. Most of these novel phosphorylase activities have been identified through the investigations of glycoside hydrolase families containing known phosphorylases. Here, the diversity of phosphorylases in each family is described in detail.