Twenty four cases of acromioclavicular seperation were admitted and treated at Severance Hospital, Yonsei University from October 1964 to September 1975. Of these, six cases were subluxations and eighteen cases were dislocations. Acromioclavicular joint injury is relatively rare and there are many methods of treatment. In our cases, all the six subluxations and seven of the eighteen dislocations were treated by conservative method, while eleven of the eighteen dislocations were treated by operative method. The results of all the subluxated cases were satisfactory. In cases of dislocation, the results were considerably better in operated cases with Weavers method.