Introduction: There has been growing interest in determining the influence of post-operative immobilization posture and rehabilitation protocol on healing rates and clinical outcomes. Current consensus calls for the use of an immobilization device post-operatively, which commonly comes in the form of a standard sling or an abduction brace with the arm positioned in varying degrees of abduction. There is a lack of high-level evidence in the literature to recommend one type of immobilization device or arm position over another. Objectives: This study aimed to summarize the current clinical and biomechanical evidence for the optimal postoperative positioning and bracing of the arm following arthroscopic rotator cuff repair. Methods: A comprehensive search of the electronic databases EMBASE, MEDLINE, and PubMed was performed using a combination of the following keywords and medical subject heading (MeSH) terms: ‘arthroscopic’, ‘rotator cuff repair’, ‘sling’, ‘brace’ and ‘immobilization’. This systematic review was conducted following the Preferred Reporting for Systematic Reviews and Meta-analysis (PRIMSA) guidelines. Two reviewers performed an independent assessment of the methodological quality of each eligible clinical study using the Methodological Index for Non-Randomized Studies (MINORS).Results: Based on current biomechanical evidence, placement of the arm into an abducted position following rotator cuff repair was found to be favorable. An abduction angle of 30° was associated with lower strain on the repair while maintaining appropriate contact pressure at the footprint. However, the use of an abduction brace did not result in a clinically significant improvement in long-term PROM, ROM, and re-tear rates when compared to a traditional sling in clinical studies.Conclusion: Despite observing favorable outcomes with abduction bracing after rotator cuff repair in biomechanical studies these findings were not reproduced in clinical studies. However, current clinical studies are comprised of small sample sizes, varying tear sizes, and significant heterogeneity in both, the degree of abduction and forearm rotation. Future studies should be directed towards prospectively investigating the effect of immobilization position among patients with similar rotator cuff tear sizes.