Open chest wounds come in a variety of shapes and sizes. Their one commonality is an open communication between the pleural space and the external environment. The wounds have often been sealed by the soft tissues of the chest wall in the vast majority of patients with penetrating injuries to the chest. The primary concern with these patients is the diagnosis and treatment of underlying thoracic, cervical, and/or abdominal injuries. Rarely, small perforations may produce a valve-like entry into the pleural space, enabling air to be “sucked in” during inspiration but blocking air egress during expiration. Thus air will continue to accumulate, leading to a tension pneumothorax requiring needle decompression followed by a tube thoracostomy. Larger, more destructive wounds of the chest may also occur. These are most common in combat injuries. In civilian practice, they are often secondary to shotgun injuries. The larger wounds are also caused by high-velocity weapons, explosions, on-the-job injuries, propeller injuries, or fencepost impalements, to name a few. Clothing, wadding, shell fragments, and pieces of the chest wall may all be driven into the thoracic cavity. Such injuries are associated with physical loss of a portion of the chest wall itself, making adequate ventilation impossible.1 These wounds are known by numerous names including open chest wounds, open pneumothoraces, sucking chest wounds, and communicating pneumothoraces. These specific open chest wounds are the focus of this chapter.