Abstract: An apparatus for sizing extruded plastics sections is proposed in which, in order to increase the heat transfer capacity between the hot plastics mass of the section and a cooling vehicle in a reduced space and to allow high production rates, there is interposed between metal block-type sizing gauges a cooling tank to be traversed by the section to be cooled between one sizing gauge portion and a subsequent sizing gauge portion. In this tank, which can also be placed under vacuum, the section is subjected to the action of a cooling fluid such as water or air which acts directly on its outer walls.