Purpose: The purpose of our study was to compare treatment results of two different surgical techniques for chronic acromioclavicular joint dislocations. Materials and Methods: Fifty consecutive patients diagnosed as chronic acromioclavicular joint dislocations between January 1997 and June 2009 were included in the study. Patients were randomized into two different groups. Patients in the first group (n=20) were treated using a modified Weaver and Dunn method using a simple coracoacromial ligament transfer method. Patients in the other group (n=30) were treated with acromial bone-block transfer containing coracoacromial ligament. Mean follow-up times for the two groups were 13.1 and 14.9 months, respectively. Results: At 1 year postoperatively, mean coracoclavicular distance, the VAS score and the ASES score for the Weaver-Dunn method group; for the bone block transfer method group were 3.8 mm (-3 to 6 mm), 3.5 (1.0 to 7.0) and 91.1 (81.66 to 95); 3 mm (-2 to 6 mm), 4.2 (1.0 to 7.5) and 79.6 (31.66 to 95). There were no significant differences in radiologic (p=0.377) and functional (p=0.093) results between the two groups. Failures in the former and latter group were, respectively, two and one. Conclusion: The bone block transfer method shows a tendency to maintain coracoclavicular distance and appeared to yield similar results as the modified Weaver Dunn method.