Disaccharide and oligosaccharide mimics are potentially more selective glycosidases inhibitors than simple monosaccharide mimics. They represent also more selective ligands for lectins and oligosaccharide receptors and can become immunostimulating agents. The biological properties of disaccharide and oligosaccharide analogs containing thiosugars (5-thiopyranoses, 4-thiofuranoses) are revised together with the methods for their obtention.