Hyperbaric oxygen has long been used for the treatment of diffuse or local hypoxic disease. Acute myocardial infarction is a very common cause of out-of-hospital cardiac arrest at the emergency room. Most of the survivors suffer various degrees of hypoxic encephalopathy. We reported two patients presenting cardiac arrest due to acute myocardial infarction and persistent impaired consciousness after successful primary percutaneous coronary intervention. Both of them had signifi cant neurological improvement after hyperbaric oxygen therapy.