This contribution describes formulation and preparation concepts for the generation of biodegradable polymer systems under the inclusion of growing-again raw materials. The incorporation of native starch into aliphatic polyurethanes as well as the degradation behaviour of such filled systems will be discussed. In a Further chapter, concepts for the generation of thermoplastic starch using a twin-screw kneader, will be presented. These destructurized polysaccharides can form the polymer matrix of flaxfibre reinforced composites. The preparation of polymer blends, composed of thermoplastic starch and biodegradable synthetic thermoplastics leads to competitive two-phase polymers including a remarkable potential of development. As a result of close-meshed structure/property interrelationships, the morphology formation during the compounding process is of utmost importance. Dimensionless characteristics will be presented that can be used to estimate and to assess the resulting phase structures.