The invention relates to a method for producing a rotor of a flow engine, namely an integrally bladed rotor with an integral outer shroud, comprising at least the following steps: a rotor blank comprising the integral rotor blades and the integral outer shroud is first produced by means of a generative production method; the rotor blank is then subjected to a separating surface treatment at flow-guiding sections and is subjected, separately therefrom, to a machining surface treatment at non-flow-guiding sections.