Congenital coronary arteriovenous fistula is a rare cardiac defect that causes coronary arterial flow to drain into the right cardiac chambers, the pulmonary artery, the coronary sinus, or the left cardiac chambers. The most frequently involved vessel is the right coronary artery. We experienced a case that had a coronary arteriovenous fistula associated with valvular heart disease. With the cardiopulmonary bypass done under hypothermia, mitral valve replacement was accomplished and the fistulas of both proximal and distal portions of the right coronary artery were closed with 3-0 prolene. Postoperative course was uneventful.