The authors have reviewed 11 cases of prosthetic replacement for severe proximal humeral fractures which were treated from March 1989 to December 1993, paying particular attention to the range of motion attained after surgery and the factors which influence the limitation of shoulder motion. The results of this study were as follows: l. Among the 11 cases, 10 cases showed sttisfactory pain relief. 2. Active motion of the shoulder averaged 91° of forward flexion, 72.8° of abduction and 35° of external rotation. 3. The humeral offset averaged 30.9mm in normal shoulder and 18.9mm in affected shoulder. 4. In 6 cases which the humeral offset measured over 20mm, active motion averaged 104° of forward flexion and 83° of abduction and 5 cases showed satisfactory results. 5. In 5 cases which the humeral offset measured under 20mm, active motion averaged 104° of forward flexion and 83 of abduction and 5 cases showed unsatisfactory results. 6. Prosthetic replacements were performed within 1 week after injury in 7 cases and among these 5 cases showed satisfactory results. The range of motion after prosthetic replacement for severe proximal humeral fracture was disappointing. We concluded that limited range of motion is mainly due to reduced humeral offset and restoration of humeral offset by appropriate reattachment of greater tuberosity will allow better clinical result.