Objectives: This study aims to investigate the effect of acromioclavicular joint (ACJ) degeneration on orthopedic shoulder tests (OST) and to determine complementary role of ACJ injections in the treatment of subacromial shoulder impingements. Patients and methods: At a secondary care center, 62 patients (56 females, 6 males; mean age 55.8±9.3 years;range 35 to 74 years) with the clinical and radiological diagnosis of shoulder impingement syndrome were enrolled to the study. Two injections were applied to ACJ and subacromial space. Patients were assessed through OSTs (Neer, Hawkins- Kennedy, empty can, full can, external rotation resistance, lift-off and cross-body adduction tests) at baseline and after injection to ACJ and subacromial space. Visual analog scale was used for overall pain. Results: Two injections and three sets of OSTs were performed on the patients. A significant difference was found in the all OSTs after ACJ injection (p<0.001). Visual analog scale scores improved significantly following both ACJ and subacromial injections (p<0.001). Conclusion: Concomitant ACJ diseases should assessed carefully in the patients with rotator cuff lesions, as it may change the type of management approach.