Oligosaccharides containing thioglycosidic linkages are resistant to enzyme-catalysed hydrolysis and therefore interesting material for studies of carbohydrate hydrolases. Some of these were shown to be competitive inhibitors for several glycanases such as α-amylase,1cellobiohydrolase I and II,2and for α-l-fucosidase,3a glycosidase. Thio-oligosaccharides have also been used to prepare column material for affinity chromatography to isolate carbohydrate hydrolases. In contrast, affinity material containing normalO-glycosidic bonds was hydrolysed and led to column deterioration. By employing this approach, affinity materials containing 1,4-dithiocellobiose and 1,4,4′-trithiocellotriose could be used successfully to separate the cellobiohydrolases ofTrichoderma reesei.2