The brachial plexus palsy is a rare complication of a clavicle fracture, occurring in 0.5% to 9.0% of cases. This condition is caused by excessive callus formation, which can be recovered by a spur resection and surgical fixation. In contrast, only seven cases have been reported after surgical reduction and fixation. A case of progressive brachial plexus palsy was observed after fixation of the displaced nonunion of a clavicle fracture. The symptom were improved after removing the implant.