The present invention relates to resorbable membranes for medical uses. The membranes according to the present invention are produced or producible from a composition comprising at least one polyol component, at least one polyisocyanate componentand an additive selected from polyvinylpyrrolidone, polyvinyl- polypyrrolidone, a copolymer of polyvinylpyrrolidone with vi- nylacetate, vinylimidazole or vinylcaprolactam or mixtures thereof. The present invention further relates to a kit comprising a multitude of membranes with different absorption rates.