Inferior subluxation of the humeral head can occur after shoulder trauma or surgery. One hundred consecutive patients were evaluated prospectively after shoulder surgery or injury. The radiographic incidence of inferior subluxation of the humeral head 2 weeks after rotator cuff repair was 10%. The radiographic incidence of inferior subluxation after fracture of the proximal humerus was 42%, and the incidence 2 weeks after prosthetic humeral head replacement was 60%. The immediate postoperative radiograph showed an inferior subluxation of the humeral head in 4% of patients after prosthesis insertion, but no subluxations were seen immediately after rotator cuff repair. Radiographs made immediately after fracture of the humerus showed a 16% incidence of inferior subluxation. The inferior subluxation resolved by 6 weeks in 92% of patients with humeral fractures, 96% of patients with humeral head prostheses, and all patients who had undergone rotator cuff repair. No subluxations were seen 2 years after injury or surgery. The treatment used--early active exercises and a sling when not exercising--was effective.