Abstract: The present invention relates to a process for the preparation of thermoplastic polyurethane by reacting a) organic and/or modified organic polyisocyanates with b) at least one oligomeric polyhydroxy and/or polyamino compound having an average molecular weight of from 400 to 10,000 g/mol, in the presence or absence of c) chain extenders having at least two Zerewitinoff-active hydrogen atoms and an average molecular weight of less than 400 g/mol, d) catalysts, e) compounds which are less than difunctional with respect to isocyanates and/or isocyanates which are less than difunctional and, f) assistants and/or additives, in a twin-screw extruder in which both screws rotate in the same direction and which has a length of/diameter ratio of from 20 to 6 and discharging the resulting thermoplastic polyurethane from the extruder with shaping.