Abstract: In a gas turbine of disc-type construction having turbine discs mounted on a rotor shaft, with rings of U-shaped cross section interposed therebetween, the turbine discs having respective rotor blades secured in blade feet thereon, and a cooling system for the rotor blade feet including axial grooves formed in the feet as well as free annular gaps located between respective end faces of the turbine discs and the intermediate rings over the radial elevation of the feet, one of the annular gaps serving as a coolant gas feed chamber and being closed radially outwardly by a sealing ring and being connected radially inwardly to radial coolant gas feed channels, the other of the annular gaps being radially outwardly open and being sealed radially inwardly against the respective turbine disc, the improvement wherein the intermediate rings are formed with bores extending axially therein from the one annular gap serving as a coolant gas feed chamber from a location close to and radially inwardly of the sealing rings,