Blends made of thermoplastic polyurethanes (TPUs) and of polylactides (PLAs) are produced via A) reaction of at least one thermoplastic polyurethane with at least one diisocyanate or one diisocyanate prepolymer which has at least two isocyanate groups, or a mixture thereof, in the melt, with reduction of the molar mass of the thermoplastic polyurethane and with formation of a thermoplastic polyurethane having an excess of isocyanate end groups, B) introduction of at least one polylactide into the melt of the stage A) product, and reaction of the stage A) product with the polylactide at a temperature below 190° C., C) cooling of the resultant blend, where no polyols are used in stages A) to C).