PURPOSE: To evaluate, if possible, the radiographic features of tuberculous osteitis in the greater trochanter and ischium, and to determine the cause of the lesions. MATERIALS AND METHODS: We retrospectively reviewed the plain radiographic findings of 14 ptients with histologically proven tuberculous osteitis involvingthe greater trochanter and ischium. In each case, the following were analyzed : morphology of bone destruction, including cortical erosion; periosteal reaction ; presence or abscence of calcific shadows in adjacent softtissue. On the basis of an analysis of radiographic features and correlation of the anatomy with adjacent structures we attempted to determine causes. RESULTS: Of the 14 cases evaluated, 12 showed varrious degrees of extrinsic erosion on the outer cortical bone of the greater trochanter and ischium ; in two cases, bone destruction was so severe that the radiographic features of advanced perforated osteomyelitis were simulated. Inaddition to findings of bone destruction, in these twelve cases, the presence of sequestrum or calcific shadows was seen in adjacent soft tissue. CONCLUSION: Tuberculous osteitis in the greater trochanter and ischium showed the characteristic findings of chronic extrinsic erosion. On the basis of these findings we can suggest that the selesions result from an extrinsic pathophysiologic cause such as adjacent bursitis.