Background: Hook plates are used to treat acromioclavicular joint dislocations. Our study took into consideration the patients’ outcome following treatment with clavicular hook plates retained for more than five months. Objectives: Our aim was to assess the response to treatment of acromioclavicular joint dislocation by clavicular hook plate when retained for more than five months. Patients and Methods: We treated 24 patients who had acromioclavicular joint dislocation with a clavicular hook plate between 2008 and 2012 at our hospital. We did not repair the coracoclavicular ligament. In all patients, the plate remained more than five months because they did not come back at the recommended time for removal of their plates. The follow-up period ranged from five to thirty three months with a mean of nineteen months. Results: The main complication was osteolysis that was seen in two patients. The mean constant score was 94.5 ± 8.77 out of 100 with a range between 70 and 100. Conclusions: Our study showed that the use of clavicular hook plates was a good treatment option for acromioclavicular joint dislocation. However, scores were lower in case of prolonged presence of plates.