Fortunately, revision surgery after prosthetic shoulder arthroplasty is rarely required. However, various complications or combinations of complications can lead to the need for revision surgery. For many of these, several treatment options are possible. Recognizing all the problems that contributed to failure in an individual patient may be difficult before revision surgery. Understanding the abnormality present at the time of surgery requires considerable experience. For example, glenoid loosening, in addition to being accompanied by scapular bone loss, may be associated with rotator-cuff tearing, instability, or joint contracture. In addition to the component loosening, all of these must also be treated if the revision procedure is to be successful. When addressing glenoid loosening, it seems to be best to revise the component, if possible. If there is extreme bone loss, one may have to bone graft the deficiencies and not replace the glenoid component. Fortunately, clinically significant humeral loosening is rare. When it occurs, revision of the component is justified and almost always possible. In hemiarthroplasties with pain, conversion to a total shoulder arthroplasty by placing a glenoid component is highly effective. In instability after shoulder arthroplasty, soft-tissue repair does not always create stability.