In recent years, substantial advances have been made in the engineering of glycosidases and glycosyltransferases for the synthesis and degradation of glycan structures. Key developments include improvement of the thermostability of xylanase through comprehensive saturation mutagenesis, creation of the first glycosynthase derived from an inverting glycosidase and the emergence of a new class of modified glycosidases capable of efficiently synthesizing thioglycosidic linkages. Of particular note is the increased use of random mutagenesis and directed evolution tactics for tailoring glycosidase activity. Although the engineering of glycosyltransferases is still in its early stages, recent work on the structure-based alteration of substrate specificity and the manipulation of glycosyltransferase profiles in whole cells to effect complex changes in in vivo glycobiology probably foreshadows a wave of considerable innovation in this area.