BACKGROUND: There is no consensus about the length of the immobilization period after receiving a Reverse Shoulder Arthroplasty (rTSA) for a cuff-deficient shoulder. The objective of this study was to determine whether patients receiving an rTSA for a cuff-deficient shoulder could be managed without any immobilization after surgery. METHODS: Prospective randomized study that included a primary rTSA implanted for a cuff-deficient shoulder. Patients were randomized into group I (3-weeks immobilization) or group II (without immobilization). Pain was assessed with the VAS the day before surgery, at 24 and 48 hours after surgery, at 7 days, at 3 weeks, and at 3, 6, 12 and 24 months. The functional outcome was evaluated before surgery and at 12 and 24 months follow-up using the Constant Score. Complications were also recorded at all the points throughout. RESULTS: A total of 64 patients were included. The mean age was 73.5 years (range, 68.5 to 79.5 years). There were 50 women and 14 men. Group 1 consisted of 32 patients and 32 were allocated to group II. There were no significant differences between the two groups in terms of age, gender and the preoperative VAS and Constant scores. No statistically significant differences were noted between the 2 groups relative to the postoperative VAS at 24 hours (p = 0.576), 48 hours (p = 0.296), 7 days (p = 0.512), 3 weeks (p = 0.114), 3 months (p = 0.823), 6 months (p = 0.623), 12 months (p = 0.388), and 24 months (p = 0.515). Neither were there any differences in the Constant Score at 12 months (p = 0.501), and at 24-months (p = 0.566). Furthermore, no complications were reported during the follow-up period in any group. CONCLUSIONS: Based on the results of this study, there is no need to immobilize the arm after receiving an rTSA for a cuff-deficient shoulder. The pain and functional outcomes are comparable to those obtained with a 3-week immobilization period.