Abstract: The invention relates to a method for producing a polymer, in particular a thermoplastic, window or door hollow-chamber profile (1), wherein the hollow-chamber profile (1) which comprises at least one hollow chamber (2, 2?) is produced by means of an extrusion production process (3), wherein, during this extrusion production process (3), continuous reinforcing fibres (5) are integrated into the polymer matrix (4) of the hollow-chamber profile (1), and wherein the extrusion production process (3) is intended to produce at least one continuously fibre-reinforced core profile (10) of the hollow-chamber profile (1), which core profile has at least one hollow chamber (2), and the core profile (10) is provided with a preferably extruded outer coating (12) to improve the surface quality of the hollow-chamber profile (1).