Progress in rolling-contact fatigue life of bearing steels encourages the reduction in size of bearings. This can lead to situations in which the bearing suffers from excessive loading. Core fracture of carburized rollers of bearings by excessive loading was investigated. The higher the core hardness, the less the core fracture happens. The critical stress amplitude at the center of the core for the core fracture was obtained in relation to core hardness.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in San Diego, California, October 22–24, 1984