A reduced retroversion angle of the humeral head may predispose to recurrent anterior shoulder dislocation and may also be a factor in persistent instability after soft-tissue repair. We performed rotational osteotomy of the proximal humerus in 20 patients with recurrent anterior shoulder dislocations (10 traumatic, 10 non-traumatic) and a decreased retroversion angle of the humeral head. The mean preoperative retroversion angle was 12 degrees, which was increased after surgery to a mean value of 32 degrees. All patients regained a normal range of shoulder motion and normal function within three months after surgery. At the five-year review all shoulders were stable, pain-free and had no radiological signs of osteoarthritis.