A key role of oligosaccharides in biological processes becoming more obvious every day. An increasing interest in this group of biomolecules is related to their broad spectrum of applications, i.e. in food, feed and pharmaceutical industries, in cosmetics and medicine. Efficient, full-scale processes that allow to produce different types of these oligomers are of graet importance. Biocatalysis is considered very attractive in comparison to the non specific, time-consuming and often environmental unfriendly chemical technologies of oligosaccharide production. Two groups of enzymes are involved in this process, transferases and glycosidase. This review describes oligosaccharide synthesis through the reactions of transfer, transglycosylation and reverse hydrolysis.