OBJECTIVE: To describe the outcomes of a surgical closure and a device closure of ASDs using an Amplatzer Septal Occluder in patients more than 40 years of age. METHODS: Between Mar 1991 and Feb 2008, 21 surgical closures of ASDs (S group) and 44 device closures of ASDs using the Amplatzer Septal Occluder (ASO group) were performed in patients more than 40 years of age. These outcomes were retrospectively reviewed and compared. RESULTS: There was no mortality and no major complication in either group. In the S group, the hospital stay was significantly longer than in the ASO group (P < 0.001). In compared to the ASO group using univariate analysis, the S group tended to have a significantly higher total incidence of postoperative atrial arrhythmias (S vs. ASD = 8/21 vs. 7/44, P = .047), however, there was no significance in multivariate analysis (P=0.348). A higher incidence of a new onset of atrial arrhythmia was observed in the S group (2/14 vs. 0/33, P = 0.074), however, both of the new-onset arrhythmias were temporary in the early postoperative period. The existence of atrial arrhythmia in the mid-to-long term period was similar in the both groups (5/21 vs. 7/44, P=0.752). CONCLUSIONS: Both a surgical closure and device closure of ASD showed satisfactory outcomes for patients more than 40 years of age. Although early postoperative atrial arrhythmia is a concern in the S group, there was no difference in the incidence of atrial arrhythmia in the mid-to-long term period.