The incidence of a fractured humeral head penetrating into the thoracic cavity is extremely rare. A 46-year-old woman presented with moderate respiratory distress at the emergency department after being involved in a motor vehicle accident. Radiographic examinations revealed fractures of the second to fifth ribs on the left side along with hemopneumothorax and fracture-dislocation of the humeral head into the thoracic cavity. After initial stabilization, video-assisted thoracic surgery (VATS) was performed to remove the fractured humeral head, and this was followed by a hemiarthroplasty. In this case report, we have discussed significant aspects of this uncommon finding in order to alert surgeons of the potential risks associated with intrathoracic displacement of the fractured humeral bone in trauma patients.