A radial impeller for a centrifugal pump with at least one flow channel between an axial flow inlet zone and a substantially radial flow outlet zone, which flow channel is limited by the inside and outside surfaces of at least one rotor blade and by first and second annular channel surfaces which substantially extend transversally to the axis of the radial impeller, face one another and are integrally arranged with the radial impeller. In order to simplify the production of the radial impeller it is provided that the channel surfaces are provided with different diameters, with the smallest diameter of the first channel surface being slightly smaller than the largest diameter of the second channel surface and with preferably the first channel surface being arranged on the side of the inlet zone of the radial impeller.