The Amplatzer septal occluder (AGA Medical Corporation, Golden Valley, MN) is designed to be an ideal device for the transcatheter closure of ostium secundum atrial septal defects. This device is user-friendly and has a complete closure rate of greater than 96% and few complications. It is easily retrievable and repositionable. It is also useful for closure of other types of shunts. Large atrial septal defects (ASDs) of up to 38 mm may now be closed. The use of the transesophageal echocardiogram (TEE) for evaluation of device placement is also reviewed.