Twenty patients with acute Rockwood type IV (3 cases) and type V (17 cases) acromioclavicular (AC) dislocations were studied. All patients underwent the same surgical technique: arthroscopic release of the coracoacromial ligament, reduction of the dislocated joint, coracoclavicular (CC) fixation with a malleolar screw and metal washer, transfer of the proximal insertion site of the coracoacromial ligament to the clavicle, CC cerclage with 2 No. 5 Ethibond sutures, and deltoid-trapezius imbrication. Clinical and radiographic follow-up was at 1 week, at 2 and 6 months, and at final evaluation (a minimum 2-y follow-up). The screws were removed 8 weeks after surgery. Postoperative radiographs were examined for the presence of degenerative changes and pain in the AC joint and used to compare the CC and AC distance between operated and nonoperated shoulders. The results were graded using the University of California, Los Angeles shoulder rating scale. Eighteen patients had a University of California, Los Angeles score of 35 and 2 had a score of 33, indicating satisfactory results. Reconstruction of the radiographic anatomy of the injured joint was achieved in all cases. If surgery is indicated, the quadruple repair technique described here is recommended for the treatment of acute Rockwood type IV and V AC dislocations.