The two accepted major methods for decompression of a pneumothorax are needle aspiration in the second intercostal space and large bore chest tube insertion in the midaxillary line, sixth, seventh or eight intercostal space. Both of these devices have drawbacks in the emergency management of a tension pneumothorax. Relating to size, case of insertion, volume of air aspirated and cumbersomeness of associated equipment. This evaluation of its effectiveness is both in the prehospital phase and in the Emergency Department by studying 40 patients, 55% of which were prehospital. Sixty per cent were placed by EMT-Paramedic personnel. All of those patients that survived their multiple trauma long enough to allow x-rays to be made, had partial to total re-expansion of the pneumothorax. Of those patients undergoing autopsy or surgical exploration no indication could be identified of pulmonary injury secondary to the insertion of the device. The only complications were: intercostal artery laceration and a minor laceration of the dome of the diaphram. In summary this study of 40 patients demonstrates the effectiveness of the use of a device for the management of tension pneumothorax, both prehospital and in-hospital by physician and EMT-Paramedic personnel.