THE fact that acutely painful shoulders are on the increase seems well established in medical circles today. Physicians, whether general practitioners, orthopedic surgeons, rheumatologists, physiatrists, or roentgenologists, all agree that they are seeing many more patients with this complaint than they did one or two decades ago. Unfortunately, however, a great deal of confusion surrounds the subject and there is no general agreement even among physicians regarding the various conditions that cause "the painful shoulder"; nor is there general agreement on all methods of treatment. Not every pain experienced in the shoulder is due to difficulty in that particular joint. Patients who have osteoarthritis of the cervical vertebrae, with narrowing of the intervertebral neural foramina, may develop pain anywhere along the course of a nerve that is subject to slight pressure. Patients suffering from generalized rheumatoid arthritis may have an acute involvement of the shoulders as part of the arthritic process. Furthermore, patients with acute, or even chronic, gall bladder disease may complain of pain in the right shoulder, and patients with heart disease may complain of pain in the left shoulder, while intrathoracic abnormalities may cause pain in either. But in all such cases, when a painful shoulder is part of a generalized arthritic process, or when it is referred or radicular pain, it is usually accompanied by other symptoms and signs which suggest the diagnosis. Therefore, it rarely causes confusion with the purely local conditions which will be discussed here.