The method of treatment of acromioclavicular dislocation is controversial, and conservative and surgical treatment have been reported to be both successful. Recently, many surgeons tend to treat the acromioclavicular dislocation with anatomical reduction of acromioclavicular joint and rigid internal fixation because of many disadvantages of conservative methods. We report 24 cases of acute acromioclavicular dislocation treated with modified Phemister method from March 1989 to December 1992. The follow-up ranged from 12 months to 31 months with 16.5 months on average. The results are as follows. l. Among 24 cases, 21 cases are males and 20 cases are in 3rd decade to 5th decade. 2. The most common cause of injuries is falling down, followed by traffic accident. 3. Associated injuries are fractures in 5 cases, spleen rupture in 1 case. 4. Except 1 case with spleen rupture, 23 cases were treated within 2 weeks after injury. 5. Preoperative difference in C-C distance on stress view is 8.6mm on average, ranged from 6mm to 18mm. 6. Clinical results were excellent in 11 cases, good in 10 cases, fair in 2 case, and poor in 1 case. 7. Complications were pin migration in 1 case and symptomatic acromioclavicular arthritis in 1 case.