We herein present a case who underwent vacuum-assisted wound closure (VAC) therapy for post-sternotomy mediastinitis. A 71-year-old female with chronic renal failure on dialysis underwent a graft replacement of the ascending aortic aorta for the treatment of an acute aortic dissection. After she was discharged from the hospital, a purulent discharge was noted to occur from the median sternal wound. The wound was therefore reopened and all sternal wires were removed. Thereafter, polyurethane foam which was shaped to fit the defect was placed within the cavity. The area was covered with adhesive drape and suction drainage was carried out at -100 mmHg. The polyurethane foam was replaced every few days. The wound was finally closed using a muscle flap at 49 days after surgery. VAC therapy is therefore considered to be a useful treatment modality for deep sternal wound infections.