Tension pneumothorax and hemothorax are life-threatening emergencies that require immediate treatment. Field stabilization of trauma patients often requires rapid surgical drainage of these injuries but inevitably delays departure for hospital. Conventional treatment involves the insertion of a chest drain but we describe a modified technique of simple thoracostomy that is faster and simpler to perform and avoids the risks associated with insertion of the chest drain. Following use of a simple thoracostomy as an alternative to chest drain insertion in 45 patients at the roadside, this technique appears to have important advantages over conventional techniques and warrants further clinical evaluation.