An 18-year-old asymptomatic male was found to have a high-flow systemic arterial to pulmonary arterial fistula fed by dilated lower intercostal arteries draining via pulmonary artery toward the left main pulmonary trunk. Transcatheter Guglielmi Detachable Coil (GDC; Target Ther, Fremont, Calif.) embolization was performed. Transcatheter embolization is a reasonable and less invasive mode in the treatment of systemic artery to pulmonary artery fistula, and GDC offers more precise coil placement over other conventional coils.