The main theme of this thesis is the development and the characterization of interpenetrating polymer network hydrogels (IPNs) based on biodegradable and biocompatible polysaccharides, in particular alginate, hyaluronic acid and dextran. The suitability of these novel systems as pharmaceutical and biomedical devices for the controlled release of proteins as well as for tissue regeneration has been investigated. Alginate and dextran derivates have been used to form injectable and in situ forming hydrogels while hyaluronic acid, together with polymerizable dextran derivates were used to prepare interpenetrating network scaffolds for tissue engineering applications.