We report our experience from 1996 through 1999, representing our initial experience with use of the Amplatzer device to close atrial septal defects. Of 46 patients taken to the catheter laboratory with the intention to close the defect, the device was permanently implanted in 40 (87%). They were aged between 1.4 and 71.8 years, with weights ranging from 7.8 to 90 kg. Both age and weight distributed into two peaks, demonstrating two different populations. The size of the devices, taking the biggest device if two were inserted, was between 9 and 30 mm. We underwent a short learning curve, but the time required for fluoroscopy, or the number of difficulties experienced, showed no connection with the size or age of the patient, nor the size of the defect itself. A suspicion that young age and small size would increase the risk and difficulties, and result in more interrupted procedures, could not be substantiated. In children no interruption was procedural. Our early experience, therefore, demonstrates that an experienced interventional team can use the Amplatzer occluder successfully to close atrial septal defects in patients of all ages and sizes, at least from 7.8 kg and up.