The clinical relevance of subacromial pathology has been recognized for most of this century. More recently, the term "impingement syndrome" has been used to refer to a spectrum of subacromial pathology, ranging from tendinitis to rotator cuff tearing, and is probably the most common cause of shoulder pain. Increased experience with arthroscopy and advances in arthroscopic instrumentation have led to the widespread use of arthroscopy to treat impingement syndrome. This evolution in treatment will undoubtedly add to our understanding of the pathology. The indications for surgical treatment and the results have not changed significantly. The often proposed theoretical advantages of arthroscopy are being investigated.