A 32-year-old male with secundum atrial septal defect underwent percutaneous transcatheter occlusion. The procedure was performed under general anaesthesia and guided by real-time 3D transoesophageal echocardiography (TEE) (i.e. 33, matrix probe 2-7 MHz). The device delivery system was advanced through a femoral vein catheter and placed in the left upper pulmonary vein. A 3D left atrial view was instantaneously obtained. The size of the septal occluder was chosen according to the balloon catheter method. A 12 mm Amplatzer device was deployed under real-time 3D TEE without fluoroscopy. The 3D views depicted the progression of the left-side disc from the left atrial cavity towards the septum. Left and right atrial views demonstrated the perfect application of the device to the atrial septum. Keeping a steady traction on the delivery rod, the right-side disc of the device was then deployed on the right atrial side of the defect. A pushing and pulling of the delivery cable ensured that the device was in a secure and stable position. Absence of peri prosthetic residual shunt was assessed by 2D colour Doppler TEE before release. Transthoracic echocardiography performed the day after ensured the right position of the device. Real-time 3D TEE is a very recent technology allowing on-line guidance of atrial septal occluder device deployment; such imaging should increase delivery safety and decrease fluoroscopy time.