Fucosylation is one of the most important types of glycosylation in carcinogenesis. Fucosylation is linked to certain processes in cell-cell interaction and dynamic regulation of growth factor receptor signaling on cell surface, and changes in fucosylation result in differences of biological phenotype in cancer cells. Eleven fucosyltransferases are involved in the synthesis of fucosylated glycans and belong to some family of fucosyltransferases. To regulate cellular fucosylation, GDP-fucose, a donor substrate of fucosyltransferases, and GDP-fucose transporter are also important. Terminal fucosylation (Lewis-type fucosylation) is associated with the synthesis of sialyl Lewis antigens, leading to cancer metastasis. In contrast, core fucosylation is linked to the regulation of membrane-anchored glycoproteins, such as growth factor receptors and adhesion molecules. Target glycoproteins for each fucosyltransferase might be different in various kinds of cancer. In this chapter, we describe the roles of fucosyltransferase in several kinds of cancer, particularly gastroenterological cancers.