Abstract A severe case of generalized osteitis fibrosa cystica due to parathyroid adenoma is reported, the tumor being located in the superior mediastinum. The case is remarkable in that the patient's symptoms date back over a period of nearly sixteen years during which time she suffered no less than four fractures and one operation for kidney stones. The skeletal involvement was extensive and included both patellas, a site which has not been previously reported. Her postoperative convalescence was marked by a fracture of the right femur, suggesting that in the postoperative care of these patients precautionary splinting might be applied to bones of the extremities which are extensively involved until some degree of recalcification has occurred.