Background The purpose of this study was to examine the impact of rotator cuff (RC) decompression and/or repair on post-operative ROM in patients with pre-operative restricted passive motion who had undergone arthroscopic subacromial debridement and/or rotator cuff repair. Potential predictors of ROM recovery such as age, sex, mechanism of injury, type of surgery, presence of an endocrine illness and having an active Worker Compensation claim related to the shoulder were explored. Methods A retrospective analysis of prospectively collected data was performed. Pre-operative stiffness measured intra-operatively was defined as flexion of < =100° or external rotation of < =30° under anesthesia. Patients who received manipulation under anesthesia or required capsular release were excluded. Results Two hundred and eighteen patients met the criteria for having stiffness under anesthesia. Twenty six patients had stiffness in both directions, 19 patients had isolated restricted flexion and 173 had isolated restricted external rotation. At six months post-operatively, a statistically significant improvement was observed on average in all disability measures (P < 0.0001). The ROM improved on average in the restricted direction at 6 months (p < 0.0001). Older age had a negative impact on recovery of external rotation (F2,216 = −5.78, p = 0.02). Being a female, having a traumatic event, having a RC repair, or suffering from an endocrine illness such as diabetes, did not have a negative impact on recovery. Patients with an active work-related compensation claim showed an inferior recovery of flexion (F2,216 = −8.76, p = 0.003). Conclusion Patients with RC pathology and concomitant stiffness showed significant improvement in ROM at six months following RC decompression or repair without the need for formal capsular releases or the performance of manipulation under anesthesia. Older patients and those with active Workers Compensation claim showed an inferior recovery in isolated directions.