Large pulmonary arteriovenous fistulas (PAVFs) are difficult for transcatheter treatment. This report presents 5 patients aged 3 to 73 years with large PAVFs who underwent successful transcatheter closure with the Amplatzer duct occluder (ADO), designed for the occlusion of patent duct arteriosus. The procedures were performed without complications and provided sustained improvement in arterial oxygen saturation and exercise tolerance on follow-up examination in all patients. The transcatheter closure of large PAVFs with the ADO is effective and can eliminate the need for surgical intervention. The newly designed Amplatzer vascular plug is undergoing clinical trials.