Disclosed is a steam turbine with a casing, wherein a turbine shaft having a thrust-compensating piston is rotatably mounted inside the casing and directed along a rotation axis, wherein a flow passage is formed between the casing and the turbine shaft. The turbine shaft has in its interior a cooling line for directing cooling steam in the direction of the rotation axis. The cooling line, on one end, is connected to at least one inflow line for the inflow of cooling steam into the cooling line from the flow passage, and on the other end, is connected to an outflow line for directing cooling steam onto a lateral surface of the thrust-compensating piston. An essential aspect is, the cooling steam discharging onto the lateral surface of the thrust-compensating piston mixes with some of the live steam and is directed back into the flow passage via a return line arranged in the casing.