Occlusion of secundum atrial septal defects (ASD) by means of percutaneous transcatheter systems is increasingly used in clinical practice. A variety of different types and models of septal occluder devices are available nowadays, amongst which the Amplatzer device (Amplatzer Medical, Golden Valley, MN, U.S.A.), is regarded as one of increasing popularity. We report a case of attempted percutaneous transcatheter closure of a large ASD in an 11-year-old boy, complicated by device embolisation to the left atrium necessitating emergency surgery.