A case of severe crush injury of the chest associated with a fracture-dislocation of the thoracic spine is reported. The chest was stabilized for fourteen days by intermittent pressure ventilation. Analgesia and sedation were achieved by constant hyperventilation, maintaining an arterial blood pH in excess of 7.5. No analgesic or sedative drugs were needed and the patient was pain-free, calm and co-operative. His impressions during the period of . controlled hyperventilation are recorded. A complete examination of acid-base balance was carried out on alternate days. The treatment of similar severe chest injuries by deliberate hyperventilation is suggested.