OBJECTIVE Main purpose of this study is to emphasize the usage and safety of transthoracic echocardiography (TTE) in percutaneous atrial septal defect (ASD) closure in appropriate pediatric cases. BACKGROUND Nowadays, percutaneous closure is preferred as treatment modality for ASD in pediatric age group. METHODS Between the dates December 2003-August 2013; 340 patients whose ASD were closed included in this study. Physical examination, electrocardiogram, TTE were done before the procedure, at the 24th hour, 1st and 6th month after the procedure. After the 6th month, routine control was done annually. Transesophageal echocardiography (TEE) was performed in 184 cases with large, multifenestrated ASD and when TTE views were poor in quality. We selected the 201 patients whose ASD diameter between 10-20 mm and formed 2 homogeneous groups according to the type of echocardiography used (TEE or TTE) in order to compare the role of echocardiography. RESULTS The demographic features of patients of 2 groups were similar. There was not any statistically difference between ASD, balloon sizing diameters between the groups. No statistically significant difference in the success, complication, and residual shunt rates was found between the groups. Procedure, fluoroscopy time, and amount were significantly higher in TEE group. When hemodynamic variables except pulmonary blood flow to systemic blood flow (Qp/Qs; right-left atrium mean pressure, pulmonary vascular resistance, and peak-mean pulmonary arterial pressure) were compared, there was not statistically difference. CONCLUSION TEE is an invasive procedure and requires general anesthesia, therefore, it should not be done routinely in ASD but only in selected cases. If the size and the anatomy of ASD is appropriate, TTE should be preferred primarily in percutaneous ASD closure.