Abstract: The present invention relates to biodegradable polyester mixtures comprising from 5% to 80% by weight, based on the total weight of components i to ii, of at least one polyester based on aliphatic and aromatic dicarboxylic acids and an aliphatic dihydroxy compound (component i) and from 20% to 95% by weight, based on the total weight of components i to ii, of at least one renewable raw material (component ii) and from 0.1% to 15% by weight, based on the total weight of components i to ii, of a component iii which is capable of forming covalent bonds with both component i and component ii. The present invention further relates to processes for producing biodegradable polyester mixtures, to the use of biodegradable polyester mixtures for producing blends, moldings, films, sheets or fibers and also to blends, moldings, films, sheets or fibers comprising biodegradable polyester mixtures.