The purpose of this paper is to review the usefulness of multiplanar transesophageal echocardiography before, during and after percutaneous transcatheter closure of secundum atrial septal defects. Transesophageal echocardiography imaging techniques,including their role in patient selection, procedural guidance and immediate assessment of technical success and complications are described and discussed in this review. Percutaneous transcatheter closure is indicated for ostium secundum atrial septal defects of less than 40 mm in maximal diameter. The defect must have a favorable anatomy, with adequate rims of at least 5 mm to anchor the prosthesis. Transesophageal echocardiography plays a critical role before the procedure in identifying potential candidates for percutaneous closure and to exclude those with unfavorable anatomy or associated lesions, which could not be addressed percutaneously. Transesophageal echocardiography is also important during the procedure to guide the deployment of the device. After device deployment, the echocardiographer must assess the device (integrity, position and stability), residual shunt, atrio-ventricular valve regurgitation, obstruction to systemic or venous return and pericardial effusion, in order to determine procedural success and diagnose immediate complications.