We present a case of an atrial septal defect (ASD) in a 59-year-old man with an indication for ASD closure who also had a history of chronic obstructive pulmonary disease. Because of his decreased respiratory function with multiple bullae in his lungs, the procedure was performed without general anesthesia under the guidance of fluoroscopy and two-dimensional (2D) transesophageal echocardiography (TEE) using a transesophageal echocardiographic microprobe (micro-TEE) (S8-3t; Philips Medical Systems, Andover, MA, USA). The micro-TEE probe was inserted into the esophagus smoothly and easily in the supine position without sedation. It revealed a deficient superior-anterior rim and adequate rims elsewhere, and the maximal diameter of ASD was measured to be 25 mm. Balloon sizing resulted in a stretched defect diameter of 29 mm using the stop-flow technique. A 30-mm AMPLATZER Septal Occluder (AGA Medical, Plymouth, MN, USA) was deployed. The micro-TEE demonstrated that both disks were on the appropriate sides of the interatrial septum and the device was not interfering with surround cardiac structures. Residual shunt flow was not detected with color Doppler. The device was released successfully without any complications. Recently introduced multiplane micro-TEE can provide adequate information about a large ASD with a less invasive procedure in adult patients. Micro-TEE has a potential to become a novel imaging option for interventions of the interatrial septum. (Echocardiography 2012;29:E94-E96)