1. Central or medullary fibrosarcoma is an entity and must be considered separately from similar tumors arising in the periosteum or parosteally as well as from true osteogenic (bone-forming) sarcomata. 2. The five-year survival rate in these tumor cases is much worse than in those of soft-tissue sarcomata of similar nature, but appreciably better than in those of true osteogenic sarcoma. 3. From our series it would seem that once a patient has survived for two years, the chance of a permanent cure is good.