Traumatic posterior glenohumeral dislocations are rare and accurate diagnosis is frequently missed because of the absence of characteristic symptoms. Posterior glenohumeral dislocations represent approximately 2% to 5% of all traumatic shoulder dislocations( 10,34) . A precise determination of the incidence remains difficult because of the frequency with which posterior dislocations go undetected. Proposed explanations for the delay in diagnosis include failure of the evaluating physician to include the condition in the differential diagnosis, suboptimal radiographic evaluation and interpretation, and coincidental injuries such as fractures that can confound the patient’s presentation (31). A systematization of the clinical and radiological approach including an X-ray and CT scan leads to an early diagnosis and allows a prompt reduction. Posterior dislocation of the shoulder is the most commonly missed major joint dislocation in the body(33). It is imperative that orthopedic surgeons develop a complete understanding of the nature of this injury and its treatment so that patients who present with this condition can be diagnosed and treated effectively. It is commonly associated with an impaction or “encoche” fracture of the humeral head (reverse Hill Sach )which causes locking of the humeral head behind the glenoid. Prompt reduction and good rehabilitation lead to satisfactory results.. Closed reduction is often obtained under general anesthesia. Patients with locked posterior dislocation should be treated based on the general condition and needs of the patient, the duration of dislocation, the size of the impression defect and the experience of the surgeon. Unsuccessful closed reduction is essentially due to a large impression fracture, delayed diagnosis of the dislocation, and anatomical neck fracture(7). Surgical intervention is necessary for old unreduced posterior dislocations. The shoulder should be immobilized after reduction in neutral or external rotation splint or brace for 4 weeks and rehabilitation with progressive passive and active physiotherapy is mandatory afterwords .