60 patients who underwent total shoulder arthroplasty for primary glenohumeral arthritis were randomized to wear a sling for 4 weeks postoperatively, with either immediate passive forward flexion and external rotation being permitted, or no shoulder range of motion being permitted during the 4 weeks. The purpose of this study was to compare immediate and delayed passive range of motion rehabilitation in terms of range of motion changes and functional outcomes at 1 year postoperatively. The results displayed no significant differences between groups at 1 year in range of motion, pain, or functional outcomes. However, osteotomy healing was greater in the delayed motion group.