In a cadaver study the success of injections in the subacromial space and acromioclavicular joint was studied. Twenty-four shoulders were dissected after separate dye injection was performed with the patient in the supine position. Subacromial bursa injection was successful in 83% (20 shoulders), but in 15 shoulders other structures were also infiltrated, including seven injections in the rotator cuff. Acromioclavicular joint injection was successful in 67% (16 shoulders), but half involved other structures. The authors believe that misplaced injections may be diagnostically misleading and potentially harmful.