Patients with atrial septal defect have an increased risk for atrial fibrillation. Increased P-wave dispersion predicts the development of atrial fibrillation. The aim of this study was to determine difference in P dispersion between transcatheter closure with Amplatzer septal occluder and surgical closure in childhood. A total of 68 children (the mean age was 7.2 plus or minus 3.3 years; the mean secundum atrial septal defects diameter was 17.3 plus or minus 5.4 millimetres) were evaluated in this study. Transcatheter closure was attempted in 41 children with secundum atrial septal defects, and the defect in 27 patients was closed by surgical techniques. P maximum, P minimum and P dispersion were measured by the 12-lead surface electrocardiography. P maximum, P minimum and P dispersion were found to be similar in patients with pre- and post-procedure (98.0 plus or minus 19.3 versus 95.1 plus or minus 23.0 milliseconds; 68.0 plus or minus 20.8 versus 67.6 plus or minus 24.3 milliseconds, 29.9 plus or minus 11.0 versus 27.1 plus or minus 12.1 milliseconds, respectively). There was no statistical significance in the comparison of P dispersion between the two groups. But in the surgical group, P-wave dispersion was decreased more significantly compared with baseline values (p-value equal to 0.03). In conclusion, there is no P dispersion between transcatheter closure with Amplatzer septal occluder and surgical closure of secundum atrial septal defect.