A 2-month-old boy developed Methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis after bidirectional Glenn anastomosis for hypoplastic left heart syndrome. After reexploration, only the skin was closed but the sternum left open, and continuous mediastinal irrigation using saline containing isodine was commenced at an infusion rate of 20-40ml/h. The sternum was closed on day 7 and irrigation was stopped on day 21. The patient was weaned from the ventilator 4 days later, and is currently in a good condition awaiting a Fontan operation.