The extraspinal manifestations of Forestier's disease are described in 21 consecutive cases; diffuse idiopathic skeletal hyperostosis (DISH) is suggested as a more appropriate description of this ossifying diathesis. Characteristic roentgen abnormalities of the spine were present in all individuals and associated with significant axial clinical complaints. In extraspinal locations, hyperostosis at ligament attachments usually occurs in the pelvis, calcaneus, tarsal bones, ulnar olecranon and patella, and is occasionally associated with clinical signs and symptoms requiring surgery. The radiographic appearance in the peripheral skeleton is frequently distinctive and allows the radiologist to suggest the correct diagnosis, even in the absence of axial radiographs.