The atrial septal defect is the 4th most common congenital heart defect with an incidence of 3.78/1000 live births. The presence of a significant atrial septal defect (ASD) with right atrial and right ventricular volume overload is an indication for closure of the defect. Surgical closure of ASD is safe and effective; however, it carries the hazards of experiencing some morbidity and residual shunting, in addition to the operative scar. In this study, we are testing the applicability and efficiency of the Amplatzer® septal occluder in transcatheter closure of ASD. Nineteen children with ASDs sized 5 mm to 20 mm, were chosen during their follow up in the cardiology clinic for trial of Transcatheter closure in the cath. lab. of Cairo University Pediatric Hospital during three successive workshops over 2 years from February 2003 to January 2005, they were divided into 2 groups by transesophageal echocardiography: Group A represents the 14 patients whose defects were suitable for closure by Amplatzer® septal occluder device and were all successful with single case showing residual small jet, Group B represents the other 5 patients who were not suitable for device closure during the workshop 2 were only suitable for surgery the other 2 needed large devices not suitable for their cardiac sizes at their ages and were postponed, the last one was postponed as his appropriate device size was not available.