The healing process and the distribution of trabecular fatigue fractures were studied on upper femora obtained at autopsy. Macroscopically, two main types of trabecular fatigue fractures were found on the basis of callus formation that in histologic sections were composed of woven and lamellar bone. A third type characterized by its vestigial callus was found only in histologic sections. Fatigue fractures were more numerous in regions of the femoral head submitted mainly to compressive rather than tensile stress. Trabeculae submitted to compressive stress had a majority of the type of fatigue fractures with an exuberant thorny callus composed of woven bone (most of them located subjacent to the subchondral bone plate), whereas trabeculae submitted mainly to tension or to minimal stress, as in Ward's triangle, had a majority of fatigue fractures with a small, smooth-surfaced callus composed of lamellar bone.