Blunt chest trauma occurs in up to 50 per cent of all fatal motor vehicle accidents and is the primary cause of death in 12-25 per cent; yet only 15 per cent of patients with chest trauma arriving alive to the emergency department require early thoracotomy. Pulmonary artery disruption from blunt trauma is extremely rare. Two patients both women, older and obese with multiple rib fractures and little pulmonary parenchymal damage are reported. Neither had injury to the aorta, heart or intra-abdominal organs. One patient survived after lateral repair of the left main pulmonary artery and the other exsanguinated from a laceration of the right main pulmonary artery. Intrapericardial exposure of the proximal pulmonary arteries may be necessary for control of hemorrhage. Trauma surgeons should be familiar with this technique. Indications for immediate thoracotomy should include: massive hemothorax (greater than 1000 ml), continued bleeding greater than 300 ml in the first hour, bleeding greater than 200 ml/hr for 5 hours, or increasing hemothorax in spite of tube thoracostomy. Close adherence to these guidelines would have allowed both patients to be explored earlier.