We synthesize novel polymers with well-defined structure by quasi-living polymerization techniques (mainly atom transfer radical polymerization (ATRP) as well as carbocationic and ring-opening polymerization), investigate their properties and search for their potential fields of application. Among the targeted new structures the branched macromolecules (graft copolymers, star polymers, hyperbranched polymers) are our main interests, but we also address the synthesis and application possibilities of block copolymers and functionalized polymers.