PURPOSE: To evaluate the clinical results after modified Phemister operation for complete dislocation of acromioclavicular joint. MATERIALS AND METHODS: Thirty-seven cases of Fifty-three cases complete dislocation of acromioclavicular joint which were treated modified Phemister operation, follow up for at least one year, were evaluated. After operation, applied Kenny-Howard brace for six weeks and removed the inserted pins at ten to twelve weeks postoperatively. The ROM exercise was started at postoperative six weeks and meticulous ROM exercise was begun at pin removal. The clinical results were evaluated with range of movement, comparision of the coracoclavicular distance after surgery with that of follow up, and complications. RESULTS: The range of motion were forward elevation 150 degree, external rotation 71 degree, external rotation at 90 degree abduction 77 degree, and internal rotation T8. The comparision of coracoclavicular distance after surgery(0,6mm) with that of follow up(1.0mm) showed no significant ligament laxity. The complication were subluxation in 2 cases, heterotrophic calcification in 3cases, broken K-wire in 2cases, pin site infection in 7cases and distal clavicle osteolysis in 3cases, which were healed at follow up radiographically. CONCLUSION: To prevent of redislocation of acromioclavicular joint, we tried to insert the pin during relatively long period for sufficient healing of ruptured coracoclavicular ligament. Although immobilization period was relatively long period, clinical results were good.