A 53-year old female was noted to have an enlarged heart on a medical checkup. A multislice computed tomography study demonstrated a giant coronary artery aneurysm measuring 10 cm in diameter and a coronary arteriovenous fistula, both located below the left atrium. Resection of the aneurysm and ligation of the feeding arteries and arteriovenous fistula were performed under cardiopulmonary bypass. As the native coronary sinus was occluded, we reconstructed the vessels draining from the aneurysm into the right atrium with an autologous pericardial patch to preserve the coronary venous blood flow. To our knowledge this is the first report of an autologous pericardial patch being successfully used to reconstruct the coronary venous flow during surgical treatment of a giant coronary artery aneurysm with a coronary arteriovenous fistula.