This study reports the use of rotational osteotomy in 10 patients with locked posterior dislocation of the shoulder. The average interval between injury and diagnosis was 155 days (range, 21-400 days). Patients were aged 40-78 years old, with an average age of 53 years. Articular impaction fracture of the humeral head involved 20-40% of the articular surface as determined by CT analysis. There were no postoperative complications except a transient axillary nerve palsy. Patients were started on immediate passive motion followed by an active program at 2-3 weeks. Using the Rowe/Zarins scale, six patients had good-excellent results, two fair results, and two poor results. The poor results were seen in cases where articular cartilage damage was advanced. Rotational osteotomy is an effective procedure at restoring glenohumeral congruity and early functional activity in the patient with locked posterior shoulder dislocation given the following criteria: (a) healthy articular cartilage, (b) a humeral head defect involving less than 40% of the articular surface, and (c) a patient who is able to participate in an active rehabilitation program.