The sequence of radiographically visible changes about the shoulder girdle following irradiation was analyzed in 49 patients who received 200 kV irradiation, in 50 who received 25 MeV betatron photon irradiation, and in 20 who received cobalt-60 irradiation. The changes were dose related and were most evident in the kilovoltage group, but also occurred following megavoltage therapy. Atrophic changes may be complicated by fracture, true necrosis, true osteitis or sarcoma. These atrophic changes have clinical significance similar to the atrophic changes that occur in skin and mucous membranes. The terms radionecrosis and radiation osteitis as applied to these changes should be abandoned since they imply a more serious process than is actually present. Biopsy should be avoided if possible since trauma and secondary infection could lead to true necrosis.