Atrial septal defect (ASD) is one of the most common congenital heart diseases (CHDs) diagnosed in children. Symptoms in ASD may be absent, but palpitations and dyspnea in children sometimes reveal a complex structural and CHD. Diagnosis is established usually by transthoracic echocardiography, but in more complex cases such as coronary sinus defect, enhanced computed tomography or cardiac magnetic resonance may be used. Indication for closure depends on the dimension and on the hemodynamical impact. There are two methods for closure: surgical and interventional. Surgery may be applied to all types of ASD, while transcatheter closure may be used only for ostium secundum ASD. The most important issue in the interventional closure is the anatomical aspect related to the position of the defect. Both methods may have complications. Complex cases in children usually are not recommended for interventional closure, surgery being the recommended method. Oversizing of the device to be implanted according to the sizing balloon and not to the initial defect diameter may give a solution for large ASDs. Interventional closure of large defects in small children with an aneurysmal, multi-fenestrated, malaligned septum, or with other CHD associated may be challenging. Complications are present for both types of closure, but they are relatively different.