Abstract: A method for producing a rotor of a turbine, particularly a steam turbine, from individual rotor parts being welded together to make a unit, includes assembling parts of a rotor required for a given turbine in a modular system having supply steam shaft ends, single rotor disks, double rotor disks, exhaust steam shaft ends and optionally condensation-end-stage drums, for producing various rotor variants. The parts of the rotor are produced at parallel times according to orders and/or taken from stock. Still required remachining of the assembled rotor during production of the parts, especially machining grooves in final form for receiving rotor blade roots in the remachining step, is minimized. The parts are joined together with low warping with a beam of high power density, preferably an electron beam. Required rotor blades are selected and the rotor disks are equipped with the blades before or after the parts are joined together. The rotor put together from the individual parts is machined in final form.