The reverse shoulder arthroplasty prosthesis was originally designed for rotator cuff arthropathy, and provided good results. Over time, the indications have expanded to include, among others, irreparable rotator cuff tears and rheumatoid arthritis, and the results have become more variable. There are also fundamental differences in the designs of the original Delta III prostheses and the later developed reverse shoulder prosthesis, and many studies that provide the results in reverse shoulder arthroplasties do not consider these 2 prostheses separately. In this systematic review, we analyze the clinical outcomes of the reverse shoulder arthroplasty in rotator cuff arthropathy, rotator cuff tears without arthropathy, and rheumatoid arthritis. We also analyze the results of the 2 prostheses separately to provide a more accurate comparison.