A 34-year-old woman was admitted to the Accident and Emergency Department in respiratory distress following a horse riding accident. She had been competing in a steeplechase event when the horse fell attempting a jump. The horse rolled on to her chest, and whilst regaining its feet, fell again crushing her chest a second time. On arrival she was conscious and maintaining her own airway, but was in respiratory distress with paradoxical chest movements and left sided surgical emphysema. Her arterial blood gases on a 100% Oz reservoir mask on arrival were: pH 7.220, PO, 7.1, PCO, 6.94, Base excess 6.0, Sa 0, 70%. Her systolic blood pressure was initially 100 mmHg, but fell to 69 mmHg. Fluid resuscitation was commenced, together with Venflon cannulation of the pleural spaces. A chest radiograph revealed multiple rib fractures bilaterally (Figure 1) with no visible pneumothorax. Bilateral intercostal chest drains were inserted along ATLS protocols, and 1100 ml and 150 ml of frank blood were drained from the left and right tubes, respectively. The drains were both noted to be bubbling through the underwater seals. She was then intubated and was ventilated with intermittent positive pressure ventilation (IPPV). A repeat radiograph was performed to check the position of the drains. Whilst in X-ray, her ventilation pressures increased and O2 saturation began to decline, her trachea was deviated to the right with reduced air entry on the left. A diagnosis of a left tension pneumothorax was made (F@uY~ 2). A Venflon was inserted in the left second intercostal space, mid-clavicular line to decompress the chest. This resulted in an improvement in both her ventilation pressures and her arterial blood gases: pH 7.340, PO, 28.1, PCO, 4.80, Base excess -4.8 on 100% 0,. A second left intercostal drain was then sited. A third radiograph (Figure 3) was taken showing that her mediastinum was no longer displaced and the lung reinflated. Her pulmonary function remained satisfactory. Her right drain and apical left drain were removed on day 7, and the remaining left drain on day 10. After 10 days in intensive care she was fit to return to the ward and made an excellent recovery.