Catheter ablation of cardiac arrhythmias in pediatric population is associated with the risk of ionizing radiation on the child. Due to a greater radiation sensitivity in children and a longer life expectancy newer techniques try to reduce the radiation exposure. A new technique for zero-fluoroscopy catheter ablation is described in a 9-year-old boy who had a left-sided concealed accessory pathway. The NAVX Ensite 3D mapping system permits catheter placement inside the venous system and movement inside the heart chambers without the use of X-rays. The success rate is similar to the techniques requiring X-rays.