An elderly woman presented with a pathological fracture of the right humerus. Progressive dissolution of the shaft of this bone took place over six months. No cause could be established and the patient refused biopsy. With only simple splintage for treatment the humeral shaft gradually reformed and re-ossified over a period of two years. The patient has been under review for four and a half years and no further pathology has come to light. The cause of the osteolysis remains obscure.