['The purpose of this study was to investigate the clinical value of real-time three-dimensional transesophageal echocardiography (RT-3D-TEE) for percutaneous transcatheter closure of multiple secundum atrial septal defects (ASDs) using a Chinese domestic occluder device.', 'From July 2008 to September 2011, 37 patients (mean age 28.4 ± 9.7 years; 24 females) with multiple secundum ASDs underwent percutaneous transcatheter closure in our institution with custom-made occluder devices. RT-3D-TEE was used to clarify the diagnosis and to help determine the operation scheme before the procedure, for real-time monitoring and guiding the operation during the procedure, and for evaluating the result shortly after the procedure.', 'The custom-made atrial septal occluders were successfully implanted in 36 patients under RT-3DTEE guidance. Twenty-seven patients were implanted with two devices and 9 patients with a single device. In two patients where the distance between the two defects was less than 7 mm (5.5 mm and 6 mm), double occluder devices were also successfully implanted. One patient underwent surgery for the complication of unstable occluder and increased residual shunt after closure. No other severe complications were observed.'] Is real-time three-dimensional transesophageal echocardiography useful for percutaneous closure of multiple secundum atrial septal defects?