A 44-year-old woman with heart murmur was admitted for cardiac examination. Echocardiography and cardiac catheterization including coronary angiography demonstrated atrial septal defect (ASD) and left coronary artery-main pulmonary artery fistula. At operation, the ASD was directly closed, and the proximal portion of coronary fistula was successfully ligated from the epicardial side and the fistula orifice was directly closed from inside the pulmonary trunk under the cardiopulmonary bypass. We report a relatively rare case of adult ASD with coronary-pulmonary artery fistula, with particular emphasis on the importance of consideration of the association of this anomaly in diagnosing congenital heart disease.