The performance and microstructural behavior of several bearing steels tested in radial ball bearings were interpreted in terms of their microstructural alterations, residual stress and resistance to tempering. The bearings were fabricated out of 52100, M-50, and M-50 NiL steels and tested under identical conditions: a radial load of 1111 kg to produce a 3.62 GPa maximum Hertzian contact stress and a speed of 3 000 rpm to produce a calculated lambda ratio of 5.5. The plastically deformed region below the ball track surface of bearings which had run for extended periods was examined metallurgically and measurements were made of the hardness and circumferential residual stress. The 52100 steel bearings exhibited a white-etched microstructure in the softened worked region. The M-50 developed much less plastic flow without work softening, and the M-50 NiL exhibited the least microstructural alteration. The 52100 bearings developed the largest compressive residual stress in the worked region, while the stresses developed in the M-50 and M-50 NiL steels were less.