A method for operating a combined cycle power plant is disclosed, which has a gas turbine installation and a water-steam cycle connected to the gas turbine installation by a waste heat steam generator and has at least one steam turbine, the gas turbine installation includes a compressor, a combustion chamber, and a turbine. To cool the turbine, air compressed at the compressor is removed, cooled in at least one cooler flowed through by water, thus generating steam, and introduced into the turbine. At least with the gas turbine installation running, prior to or during the start-up of the water-steam cycle, waste heat, which is contained in the steam generated in the at least one cooler, is used to good effect for pre-heating the installation inside the combined cycle power plant.