In previous papers, one of us1has presented the experience at the University Hospital with giant cell bone tumor during the period from 1923 to 1931. To codify further that experience as a guide in the management of this lesion, the methods used and the results accomplished have been surveyed again in the same group of patients and in an additional number under observation in the department of roentgenology since that time. The current series reported includes eighteen of the previous group and twenty-two additional cases, a total of forty. Although errors in diagnosis of giant cell bone tumor may be made from the roentgenographic examination, in the large majority of cases the film evidence should be sufficient for diagnosis. In twenty-five of these, biopsy or a surgical specimen has affordedmicroscopic proof of the roentgen diagnosis. The other sixteen are typical in roentgenographic appearance and are in accord