The indications for prosthetic replacement and proximal humeral fractures include those four-part fractures and fracture dislocations, head split fractures, fractures associated with an impression defect of more than 50% of the articular surface, and some three-part fractures in which the quality of bone is inadequate to permit rigid internal fixation for early motion. The technique for proximal humeral replacement arthroplasty emphasizes accurate identification of each displaced segment so the proper treatment method may be selected, and a technique which emphasizes maintaining the deltoid origin, utilization of the biceps tendon as a guide to the orientation and identification of fracture anatomy, proper prosthetic selection, maintaining proper tension in the cuff and deltoid musculature, secure tuberosity and rotator cuff repair, bone grafting at the tuberosity shaft junction, and careful attention to postoperative rehabilitation. Although a technically demanding procedure, careful attention to patient selection, the details of surgical technique, and postoperative rehabilitation often result in excellent pain relief and satisfactory strength and patient function.