Transcatheter closure of atrial septum defect (ASD) with a closure device is increasing, but the history of clinical use of this procedure is still short, and the efficacy and long-term safety remain unproved. The total number of closure devices implanted throughout the world has not been counted accurately. Therefore, the probability of complications occurring after implantation is uncertain. Device-related complications that occur suddenly late after implantation are life-threatening, and quite often necessitate emergency surgical intervention. In Japanese medical journals, authors reporting closure devices have mentioned no complications and problems in their facilities. Detailed studies of device-related complications and device removal have not been reported in Japan. In fact, this literature search found an unexpectedly large number of reports of various adverse events from many overseas countries. When follow-up duration is short and the number of patients is small, the incidence of complications cannot be determined. Rare complications may emerge in a large series with a long observation period. Consequently, the actual number of incidents related to ASD closure devices is possibly several times higher than the number reported. Guidelines for long-term patient management for patients with an implanted closure device are necessary and post-marketing surveillance is appropriate. Development of a national database, a worldwide registration system, and continuous information disclosure will improve the quality of treatment. The devices currently available are not ideal in view of reports of late complications requiring urgent surgery and the need for life-long follow-up. An ideal device should be free from complications during life, and reliability is indispensable.