Objectives: Postoperative stiffness following arthroscopic rotator cuff repair (aRCR) is a major cause of morbidity reported in up to 23% of patients. Angiotensive converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB), medications commonly used to treat hypertension, affect TGF-β, an essential regulator of both the inflammatory process and tissue healing that has been linked to the development of tissue fibrosis. Statins, a class of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, have downstream cytokine effects thought to impact bone formation and resorption. The purpose of this study is to: determine if there is an association between ACEi, ARB, or statin usage and post-operative range of motion (ROM) following aRCR, determine if ACEi, ARB, or statin usage has any association with post-operative patient-reported outcome measures (PROMs) following aRCR, and to determine if ACEi, ARB, or statin usage has any association with the need for follow-up shoulder procedures following primary repair. Methods: This was an IRB approved retrospective cohort study examining all patients at a single institution undergoing primary aRCR from 1/1/2016 – 12/31/2019. Patients were identified by CPT codes and included if they had a minimum of 1-year postoperative follow-up and documented ROM outcomes. Patients with concomitant adhesive capsulitis, calcific tendinosis, glenohumeral arthritis, labral tears, prior history of shoulder surgery, previous history of humeral fractures, workman’s compensation claims, age under 18, irreparable rotator cuff tear, history of substance abuse, or on dialysis were excluded. Patients were then separated into four groups based on usage of ACEi, ARBs, statins, or control. Demographic information, medication usage, concurrent diagnoses, and follow-up procedures were collected via chart review. Physician and physiotherapy notes were examined to determine ROM (flexion, abduction, internal rotation (IR), and external rotation (ER)) (Figure 1). PROMs were assessed through the American Shoulder and Elbow Surgeons (ASES), Single Assessment Numeric Evaluation (SANE) and Simple Shoulder Test (SST). Results: After applying inclusion/exclusion criteria, 125 patients were included in the case group (ACEi 45 patients, ARB 27 patients, statins 53 patients) and 217 controls. No significant differences were found between groups with regard to demographics. Preoperatively, patients on ACEi or ARBs had significantly decreased active flexion (p=.022), IR (p=.002), and abduction (p<.001). Patients on statins had significantly decreased active abduction (85° vs. 130°, p=0.015), ER (40° vs. 50°, p=0.008), and IR (4 vs. 5, p=0.011). Postoperatively, patients on ACEi or ARBs had significantly decreased 6-month active ER (p=.015) that resolved by 12 months, and 6-month active abduction (p=.047) that also resolved by 12 months. Patients on statin medication had significantly increased 6-week active abduction (95° vs. 58°, p=0.017) that normalized to the control group by 3 month. All other ROM measurements at different time points were not significant. There was a significant decrease in postoperative SST scores in those taking ACEi or ARBs (p=.004), with no significance found in the other PROM scores at the 1-year mark. No significant differences were found in complications or reoperation rates between groups. Conclusions: Patients on ACEi or ARB medications are at an increased risk of decreased ROM before and 6 months after aRCR. Sub-analyses revealed that this effect was more pronounced with ACEi than with ARBs. Patients on statin medications are at an increased risk of decreased ROM before arthroscopic rotator cuff repair but increased ROM in the early postoperative period, especially abduction. Surgeons should use this information to guide patient education and rehabilitation perioperatively after arthroscopic rotator cuff repair.