Objectives. To compare the failure ratio and inhospital complications across three age groups of patients and to investigate the effects of balloon sizing on the success and the device diameter. Methods. This retrospective review was of 665 patients who had been listed for transcatheter-based closure of ASD between 1999 and 2010. The patients were divided into three age groups: children (<18 years; n = 183), adults (18-50 years; n = 337), and older adults (>50 years; n = 145). Procedural outcomes and early complications were reviewed. Use of balloon sizing was explored for its benefits. Results. Overall, failure of closure was 6.6% (n = 44). Use of balloon sizing tended to lead to a smaller device/defect ratio that was comparable to procedures without balloon sizing, though it did not predict the success rate (OR 1.4, 95% CI 0.7-2.3). Seven patients reported device embolization (1%). No mortalities were noted. In-hospital complications were 3.4%, with common complications, being vascular complications (1.4%) and cardiac arrhythmia (1.1%). No differences in failure rate or events were found among the three groups. Conclusion. Transcather closure of ASD is feasible and safe, regardless of the patient's age. A low rate of early complications was noted. Balloon sizing does not aggravate an oversizing of the device, but does not predict success.