We sought to assess the effects of transcatheter closure of atrial septal defect (ASD) on right and left ventricular form and functions, as well as atrial volumes and pulmonary venous flows. We enrolled 25 patients (mean age: 9.02) prospectively who underwent successful transcatheter closure of secundum ASD. We performed transthoracic echocardiography, including two-dimensional, pulsed wave Doppler, M-mode echocardiography, and tissue Doppler imaging before the procedure and 1 day, 1 month, 3 months and 6 months after the procedure. Serum brain natriuretic peptide (BNP) levels were measured prior to the procedure, and 1 day, 1 month, and 3 months there after. Mitral inflow early diastolic wave increased significantly, while isovolumetric relaxation time and deceleration time did not change during the follow-up. The E/E' was also increased significantly during follow-up. After the closure, right ventricular size and right atrial volume reduced, while left ventricular size increased significantly. There was a statistically significant improvement in left and right ventricular Tei indices. Pulmonary vein systolic velocity and the ratio of systolic to diastolic wave decreased, while atrial reversal wave (ARW) velocity increased immediately after the procedure. Although the concentration of BNP was increased on the first day after the procedure, its levels reduced and had reached the pre-procedure values at 1 month of follow-up. In the study, a significant improvement in the right and left ventricular functions was detected after transcatheter closure of secundum ASD in the short-term follow-up. In addition, we found a significant reduction in right heart sizes with corresponding global functional improvement in the right ventricle after the procedure.