Background: Subacromial Impingement Syndrome is the common cause for shoulder pain caused due to pathology in one or more of the structures present in the Subacromial area. The discomfort is linked to a loss of shoulder function and difficulty performing regular everyday activities. The pathophysiology is not entirely understood. The Subacromial injection was developed to reach a high drug concentration at the site of pathology while using a less overall drug to avoid systemic side effects. Triamcinolone Acetonide produces both anti-inflammatory and direct analgesic benefits in the shoulder. Material and Methods: This study included 55 patients with Age more than 20 and Pain during Shoulder Arc of Motion, Positive Neer’s Sign and Hawkin’s Test. Pain during Shoulder Arc of motion, Visual Analogue Scale Score and Shoulder Pain and Disability Index was calculated pre injection and post injection at 2,6 and 12 weeks. Data was collected and analyzed statistically. Results: 55 cases were worked up on OPD Basis. Mean age was 50.69, Male dominance. Pain during Shoulder Arc of Motion which was initially present in all 55 patients decreased over the follow-ups and at the end of 12 weeks only 3 patients had persistent pain. Visual Analogue Scale Median at 0 weeks was 9 which decreased to 0 at 12 weeks, Shoulder Pain and Disability Index Median at 0 weeks was 82.3 which decreased to 3.07 at 12 weeks. All these changes were significant with p value < 0.001. Conclusion: We conclude that in our patients suffering from Subacromial Impingement Syndrome post subacromial injection under C-ARM guidance with Triamcinolone Acetonide, the results measured by Pain during Shoulder Arc of Motion, VAS Score and SPADI showed significant improvement. Thus, We support that Subacromial injection of Triamcinolone Acetonide is safe, economical and effective in the treatment of patients suffering from Subacromial Impingement Syndrome