Three unusually interesting examples of desmoplastic fibroma—a benign bone tumor of fibroblastic origin described previously as a separate entity only by Jaffe—are presented. These were of unusually large size and occurred in areas not previously noted. Two of the tumors crossed into the epiphyseal areas of bone—a behavior not previously recorded. The lesion occurs in a wide age range with no significant sexual predilection. The symptoms vary with the size and location of the tumor. On gross examination the tumor is white or gray-white with a uniform, tough, rubbery consistency and contains occasional loculi of yellowish fluid. Roentgenographically it is a radiolucent, usually centrally located lesion that may expand the bone, having a slightly sclerotic and apparently trabeculated border. Microscopically the lesion consists of abundant, richly collagenous, intercellular material devoid of bone formation in which there is a relatively small number of small, consistently similar fibroblasts of benign appearance. Treatment should consist in incisional biopsy and then curettage or resection as required by the individual case. Amputation should rarely if ever be necessary. The tumor may be clinically and histologically easily confused with fibrosarcoma, thus an accurate diagnosis is necessary in determining proper therapy. It is suggested that other examples of this tumor exist in other institutions, probably classified as well differentiated fibrosarcoma.