During the period from Jan. 1, 1942, to Oct. 1, 1945, 656 patients were admitted to an army hospital designated as a radiation therapy center. Of this number, 25 had primary bone tumors, including 10 giant-cell tumors in the diagnosis or treatment of which we participated. A number of other giant-cell tumors were seen in consultation with other installations or as follow-up cases. Our opinions are influenced, also, by our experience prior to active military service and to some extent by the views of others as expressed in various publications. No statistical study will be attempted; cases presented are illustrative of certain features of the disease. In this hospital all cases were seen by a tumor board composed of a radiologist, pathologist, surgeon, and internist, and by representatives of appropriate specialties in selected cases. The decision as to the method of treatment was made by this board. Those desiring a review of the historical aspects of giant-cell tumors are referred to the bibliography. Im...