I propose to discuss briefly the occurrence of osteogenic sarcoma as a complication of Paget's disease of bone. I may say at the beginning that I have a vivid recollection of Dr. Harvey Cushing's presenting such a case to a group of students during a third year medical course in surgery, the site of the sarcoma being the superior aspect of the skull and the patient an elderly woman. That case was followed to its termination at the Peter Bent Brigham Hospital during the school year, and I recall that at that time Dr. Cushing advised us that sarcoma occurred as a complication of Paget's disease in 7 per cent of the cases. It is noted that Geschickter and Copeland1 in their book "Tumors of Bone" stated that this complication occurs in from 5 to 7 per cent of cases of Paget's disease. In a recently published volume on