Thirty-one patients who were unable to abduct the involved arm after reduction of a primary anterior dislocation of the glenohumeral joint were found to have a ruptured rotator cuff. All of the patients were more than thirty-five years old. Twenty-nine of them were initially presumed to have had an injury to the axillary nerve, although this injury was confirmed in only four of the twenty patients who had electrodiagnostic studies. In eight patients, the subscapularis tendon and anterior part of the capsule had ruptured from the lesser tuberosity. Recurrent instability developed in all eight patients, and repair of these structures alone was successful in restoring stability. The association between primary anterior dislocation of the glenohumeral joint and rupture of the rotator cuff in the older patient who cannot abduct the arm after reduction is poorly appreciated, as it is often missed. In our series of such patients, the incidence of injury to the axillary nerve was 7.8 per cent, as compared with 100 per cent for rupture of the rotator cuff. However, the comparative rates of occurrence of these two entities in older patients who have an anterior dislocation have not been determined.