Acoromioclavicular dislocation occurs frequently in young athletes and recently in automobile accident victims and laborers, and there are various kinds of operative methods for this injury. Authors performed operative treatment for 45 cases of acromioclavicular dislocation: 30 cases of modified Phemister operation and 15 cases of modified Bosworth operation from March 1992 to June 1996. Authors analysed the result of the treatment and the results obtained were as follows. 1. The clinical results evaluated by Weitzman criteria were all satisfactory in both modified Phemister method and modified Bosworth method. 2. The radiologic results were evaluated by the difference of the distance from the coracoid process to the clavicle between the normal and the injured site. And the result was more satisfactory in modified Bosworth method. 3. There were less complications in modified Bosworth method.