Introduction. The purpose of this study was to assess the rate of revision subacromial decompression and identify different pathologies. Materials/Methods. We analysed the patients who underwent Revision Arthroscopic Subacromial decompression from our prospective database of shoulder patients. Between April 2003 and Dec 2010, 797 patients underwent arthroscopic subacromial decompression. Patients who underwent any other procedure i.e. biceps tenotomy, capsular release, cuff repair were excluded from the study. Of these, 37 underwent a revision subacromial decompression (Revision rate 4.6%). The indication for revision procedure was persistent pain or restricted movements not responding to physiotherapy and injections. Results. We found that 1) Patients having cuff pathology i.e. partial tear or degenerate cuff were more likely to need a revision procedure (11/37 and 92/797, p = 0.001). 2) The rate of ACJ excision done for residual pain after primary subacromial decompression was similar to the rate of ACJ excision at the time of the primary procedure (7/37 vs. 100/797, p= 0.5). 3) Presence of Calcific deposits did not have any influence on the risk of having a revision procedure (2/37 and 12/797, p= 0.1). 4) Patients found to have synovitis in the primary procedure were more likely to need revision procedure (10/37 and 81/797, p = 0.001). 5) Presence of biceps tendonitis did not significantly affect the risk of having a revision procedure after arthroscopic subacromial decompression (3 /37 and 21 /797, p = 0.5). Conclusion. Our revision rate is similar to those published in literature. In our failed cases there was a trend for patients to have an associated partial rotator cuff tear and synovitis