1. Twenty-four cases of bone sarcoma which followed x-ray or radium irradiation of bone are reviewed. All except six of these occurred in association with chronic joint infection.
2. Three cases are added which are regarded as bone sarcoma/resulting from irradiation of bone for earlier independent tumors. Two are chondrosarcoma, and one is fibrosarcoma with tumor cartilage.
3. In all cases except one, the amount of irradiation was large and was administered in fractional doses over a long period.
4. The interval between irradiation and recognition of irradiation-produced sarcoma is long. The median time in reported cases is six years.
5. Chondrosarcoma occurs more frequently among irradiation-produced sarcomata than in other bone tumors.