Abstract: In a medium-pressure steam turbine of single-flow chamber type design, for use as a ship's turbine, cooling steam is conveyed via holes in the wall of the inflow part for cooling the rotor surface and the first few rows of rotor blades. The cooling steam is guided by a baffle at the wall of the inflow part to annular spaces between the shaft seal of the guide vanes and the rotor surface and via axial cooling ducts in the rotor to the bases of the rotor blades. At each rotor blade of the rows connected by the axial cooling ducts, radial connecting canals are provided in the blade bases for guiding the cooling steam into axial canals which connect the annular spaces under the shaft seals of the adjacent guide vanes.