Glycosyltransferases control the biosynthesis of glycans expressed in cells. Alterations in glycosylation in the gastrointestinal tract stem from deregulation of glycosyltransferase expression. These modifications can be detected in situ by cell and tissue immunolabelling techniques which are highly informative in physiological and pathological contexts. The protocols described here are single and double-labelling immunofluorescence techniques that allow the detection of a specific glycosyltransferase and, in the case of double labelling, the concomitant detection of the glycosyltransferase and its glycan product.