We evaluated the results of treatment in twenty-three patients with twenty-four shoulder dislocations that had gone unreduced for at least three weeks. Fourteen dislocations were posterior, eight were anterior, and one each was superior and inferior. Seventy-nine per cent of the posterior dislocations had not been recognized by the initial treating physician. Fourteen shoulders (58 per cent) were operated on. Of seven that were treated by open reduction with preservation of the humeral head, the results in two were graded as excellent; in three, as good; and in two, as fair. A Neer total shoulder-replacement prosthesis was used in one patient with an excellent result, and a Neer humeral-head prosthesis was used in two patients with a good and a fair result. In four patients, the humeral head was removed and a Jones procedure was performed, with one good and three fair results. There were no poor results after surgical treatment and it was not necessary to arthrodese any shoulder. We did not find it necessary to transfix the shoulder joint by screws or pins, or to use plaster spica casts to maintain stability of the shoulder following open reduction. Supporting the arm at the side in a position posterior to the coronal plane for a posterior dislocation, and anterior to the coronal plane for an anterior dislocation, proved to be comfortable and effective. There were no postoperative dislocations using this simple method. These results show that the over-all prognosis for surgical treatment of the chronic unreduced dislocation shoulder is more favorable than has previously been reported. A rating system based on 100 units was used to evaluate our final results, and is recommended as a standard system for future comparative studies.