32 patients were included in this study comparing ultrasound-guided corticosteroid injection to ozone injection for the treatment of shoulder impingement syndrome. The primary outcomes of interest were pain on a Visual Analog Scale (VAS), the Constant score, and the Shoulder Pain and Disability Index (SPADI) score. Secondary outcomes of interest included range of motion, subacromial bursa thickness, supraspinatus tendon thickness and acromiohumeral thickness. Follow up was performed at 2 weeks and 2 months post-injection. Results revealed significantly greater improvement in all primary outcomes in the corticosteroid group compared to the ozone group. No significant differences in improvement in secondary outcomes were observed between the two groups.