Hydrogen influence on fatigue crack propagation of the 8Mn8Ni4Cr (EFC21W) and 18Mn18Cr (P900) austenitic non-magnetic steels, which are the most widely used in the production of rotor retaining rings for turbogenerators was studied. Endurance limits and the crack growth rate of this steels on air, under electrolytic hydrogenation and dynamic loading has been investigated. Hydrogen enhances the micro brittle fracture of both 18Mn18Cr and 8Mn8Ni4Cr steels, but modern 18Mn18Cr steel exhibits a higher hydrogen embrittlement resistance as well as higher fatigue resistance on air.