Investigates the pitting and bending strength of gas nitrided steel gears made of modified 39CrMoV13.9 (a 3% CrMoV type alloy). Characteristics of the compound layer and the diffusion zone are examined. Residual stresses in the nitrided case are shown after long nitriding times. For bending strength@ additional damage line investigations were performed. The load carrying capacity of the modified 39CrMoV13.9 steel is discussed and compared with other carburized@ gas@ and ion nitrided gears.