Although SASD corticosteroid injections has been proven effective in treatment of chronic subacromial bursitis, in clinical practice, some patients fear the side effects of the corticosteroids. In the last few years, hyaluronic acid (HA) injection has been used for treatment of different kinds of shoulder disorders, including subacromial impingement syndrome, frozen shoulder, and rotator cuff tears, with variable results. However, treatment of chronic SAB with hyaluronic acid has never been reported before. Besides, some authors used combination of normal saline and lidocain as the placebo, which might not be a true placebo because lidocain can be an active medicine. Therefore, the purpose of this study is to compare the effectiveness of SASD corticosteroid, HA, and normal saline injection in treatment of patients with chronic SAB.