The authors conducted a blind retrospective survey of the clinical records and radiographic examinations of 100 patients with juvenile rheumatoid arthritis to ascertain the cause of the joint calcification observed in several cases. Review of the clinical histories showed that 39 patients (92 joints) had been treated with intrasynovial corticosteroids, while an independent study of the radiographs of the same 100 children revealed 20 cases of calcification involving 32 joints. All of the calcified joints had been injected with intrasynovial corticosteroids on one or more occasions. The frequency of calcification, its morphology, and the possible pathogenesis are discussed.