The four-part fracture and fracture dislocation of the proximal humerus in adults rated 2% only in all proximal humerus fractures, but they were reported most difficult to treat. And the high incidence of avasclar necrosis of humeral head was also reported. This led Need to recommend primary hemiarthroplasty for four-part fracture and fracture dislocation. Based on Neer's work, hemiarthroplasty has now become widely accepted for the management of the four-part fracture and four-partfractur dislocation of the proximal humerus. The purpose of this study of small series is to analyze the results of the prosthetic replacement in comminuted proximal hemeral fracture according to Neer's classification. The results of the study were as follows; 1. The average age was 65 years. 2. According to the classification of Neer, four-part fractures were three (43%) and four-part fracture dislocations were four (57%) 3. The prosthetic replacement was performed within one week in two patients, the rest five were performed after one week. 4. All seven cases were treated with hemiarthroplsty and followed from 14 months to 32 months, averaged 23 months. 5. The results were analyzed according to Neer's criteria and only two cases showed satisfatory results. 6. The most common complication was limit of range of motion due to joint stiffness (71%) 7. Finally, the factors affecting results were injury severity and early operation, proper and secure reattachment of the rotator suff, maintence or restoration of the initial humeral length, persistent and devoted physical therapy program.