The best treatment for Rockwood type III injuries is still controversial. During a retrospective study, 24 patients who were treated surgically with a hook plate and 17 conservatively treated patients were examined with a mean follow-up of 34 months. The Oxford Shoulder Score, Simple Shoulder Test, and Constant score were assessed at the follow-up examination. Stress radiographs of both shoulders were taken, and the coracoclavicular distance, as well as the width of the acromioclavicular joint, was measured. The mean Constant score was 80.7 in the conservatively treated group and 90.4 in the group that underwent surgery. The mean coracoclavicular distance was 15.9 mm in the conservatively treated group and 12.1 mm in the surgically treated group. These differences were significant (P < .05, Mann-Whitney U test and Student t test). In this study, better results were achieved by surgical treatment with the hook plate than by conservative treatment.