The present knowledge about alloarthroplastic is given in a short summary, pointing out the special importance of the isoelastic prosthesis. The importance of a long term observation is pronounced and demonstrated by the first isoelastic shoulder prosthesis implanted 10 1/2 years ago, after resection of a semimalignant caput humerus tumor. During this time no pain, incompatibility, stress protection or loosening of the prosthesis could be observed. The bone reaction during the time of fixation is described. Within 10 1/2 years the mobility of the prosthesis as part of the shoulder joint has decreased, which is probably explained by a shrinking of the shoulder joint capsule.