The acromioclavicularr joint is a common but sometimes overlookedsource of shoulder problems. Degeneraive disease of the AC joint frequently accompanies extrinsic impingement and cuff decompression and must be addressed at the same as decompression and /or cuff repair Conversely, AC disease may also be isolated and must be distinguished fom and treated apart forn the rest of the uninvolved shoulder. The diagnosis and arthroscopic treatment of acromioclavicular disease will be the focus of this presentation.