Glycogenes encode proteins involved in glycan synthesis, such as glycosyltransferases, sulfotransferases and sugar-nucleotide transporters. The comprehensive identification and functional analysis of human glycogenes has been ongoing for some time. During the past 20 years, 183 human glycogenes have been cloned and their substrate specificities analyzed. All current information on these human glycogenes and their links with orthologous genes in other species is summarized in the GlycoGene database. In recent years, two glycogene families, beta3-glycosyltransferases and beta4-glycosyltransferases, have been identified and analyzed in particular detail.