Post-traumatic pneumatoceles (traumatic pulmonary pseudocysts) after blunt thoracic trauma are not frequently observed. It is widely accepted that pneumatoceles are caused by compression of the lung resulting in bursting parenchyma, followed by decompression of the chest with negative intrathoracic pressure. We present a case of post-traumatic pneumatocele in a nine-year-old girl who was crushed under the tailboard of a horse hamper. A multislice CT of the thorax clearly demonstrated a bronchial laceration pointing to bronchial disruption as an additional causative mechanism.