Proximal humerus fracture is a common arm trauma and rarely occurs with vascular injury which however is a serious complication. In this case report, we present a long segment dissection of the axillary and brachial arteries as a rare complication due to fragmented proximal humerus fracture and shoulder dislocation. An 80-year old female patient was seen at the emergency department. Radiograph examination has revealed a fragmented proximal humerus fracture besides dislocation of the head of humerus towards the axillary area. On vascular examination, acute arterial occlusion such as absence of radial and ulnar pulses were observed in her left hand. The patient was immediately taken to the operating room. The dissection included the entire segment approximately 20cm between the distal subclavian artery and the distal brachial artery. This injured segment was removed and a 6mm Polytetrafluroethylene (PTFE) graft with rings was interpositoned between subclavian and brachial arteries. This case is a rarity because of such a significant complication after a small injury. Axillary artery injuries caused by humeral neck fractures are rare but should not be missed by the physician.