A 33-year-old patient was hospitalized after a blunt chest trauma with a left flail chest. Six hours after admission to the intensive care unit the patient suddenly developed hypotension and tachycardia. His left chest tube drained 1.5 l of blood within minutes. Immediate resuscitation and emergency sternotomy with left anterolateral extension was performed for pericardial tamponade secondary to left ventricular perforation due to a sharp rib fragment. Outcome was favourable and the patient was operated on for his flail chest by internal stabilization the next day.