A congenital fistulous communication between the coronary artery and the cardiac chamber or the pulmonary artery is a rare condition, but increasing cases with this anomaly are being recognized with wide spread use of cardiac catheterization and coronary arteriography. Recently we experienced one case of right coronary artery fistula which was associated with atrial septal defect. The patient was a 24 year old female who was admitted because of cardiac murmur, palpitation and dyspnea on exertion after pregnancy. Cardiac catheterization and selective coronary arteriography revealed that a fistulous communication, forming a large aneurysm, was noted from the right coronary artery emptied into the right ventricle. On the operation field, the right coronary artery was curved and markedly dilated from the aorta to the middle segment at acute margin of the right ventricle. The egg-sized aneurysm of dilated right coronary artery was noticed on right ventricle. The aneurysm was incised longitudinally and both the proximal opening and the termination site of the fistula were closed directly with aneurysmectomy. The right atrium was also opened to evaluate the fistulous termination site and repaired only small interatrial septal defect. Postoperative course was uneventful and she was discharged without problems