The present invention relates to a high efficiency fixed displacement vane pump. A vane pump for an automatic transmission includes a housing which may be spaced from the axis of the transmission input shaft axis and driven by a chain or gear train driven by the torque converter hub or disposed on and about the axis of the transmission input shaft and driven at engine speed. The vane pump includes a pair of port plates which reside on the end faces of a pump body having a cylindrical chamber which receives an eccentrically disposed rotor that is coupled to a stub shaft. The rotor includes two halves that define a central chamber. The rotor also includes a plurality of radial slots which receive a like plurality of vanes. The outer ends of the vanes are in contact with the wall of the cylindrical chamber and the inner ends are in contact with a single vane ring received within the central chamber.