IT IS THE PURPOSE of this paper to document two cases of pigmented villonodular synovitis of joints with bony invasion. McMaster1has recently presented a paper on this subject and added 6 new cases, bringing the total reported to 16. The new cases reported here are significant because of the joints involved and the ages of the patients. Report of Cases Case 1. An 82-yr-old woman was first seen on March 21, 1959, because of intermittent pain of many months' duration in her right shoulder. During the 2 weeks prior to her first visit, swelling had appeared and gradually increased. Pain had become quite severe and was vaguely localized at the lateral aspect of the shoulder. The patient noticed limitation of motion in abduction and external rotation. There was no history of injury or of bleeding diathesis. Physical examination revealed marked fluctuant enlargement of the entire shoulder with no