Acromioclavicular dislocations represent over 10% of acute traumatic injuries to the shoulder girdle. The mechanism is usually a direct impact on the shoulder with the arm in adduction, producing rupture of the acromioclavicular (AC) ligaments, then of the coracoclavicular (CC) ligament, with displacement of the lateral end of the clavicle. Rockwood described 6 grades of injury. Physical examination usually provides the diagnosis, which is confirmed by radiological examination. X-rays centered on the AC joint, if necessary with forceful adduction of both shoulders or under traction, are useful to evaluate the severity of the lesion. Grade I and II lesions are usually treated conservatively by simply immobilizing the arm for 3 to 4 weeks. Surgical treatment is usually advocated for grade IV, V and VI lesions: AC or CC fixation, sometimes associated with ligament repair, depending on the surgeons. AC pinning or C-C screw fixation are the techniques most often used. Management of grade III lesions remains controversial. Some authors advocate immediate surgical treatment in young, active patients, in heavy laborers and even in slender individuals. The choice of the operative technique is controversial, as no single technique has clearly proved to be superior to others. Other authors advocate conservative treatment, which gives functional results which patients consider quite acceptable, with faster recovery; patients should be informed that results are essentially similar, whatever the treatment. The possibility of performing secondary operations with good results in cases with failure of conservative management is a further argument in favor of applying conservative therapy first in acute injuries.