Diaphragmatic rupture is an uncommon and frequently missed complication in blunt thoraco-abdominal trauma. Symptoms usually become apparent in a delayed phase, up to years after the trauma. An acute presentation is extremely rare and acute tension gastrothorax in which trapping of air in the intrathoracic stomach causes mediastinal shift and lung compression, as in tension pneumothorax, is exceptional. We only found two cases in the literature. We present here two other cases from our practice, with a review on the literature on post-traumatic diaphragmatic hernias.