In patients with congenital heart disease who have undergone palliative surgical interventions postoperative arrhythmias frequently complicate the clinical course. Intraatrial reentrant tachycardias (IARTs) are one of the most common forms of postoperative arrhythmias in these patients and can lead to significant morbidity and even mortality. Drug therapy and/or antitachycardia pacing have been disappointing. Ablative therapy with radiofrequency energy offers a potential for cure for these patients but the conventional approach using multielectrode recordings and fluoroscopic guidance is technically difficult and provides limited success. Recent development of a novel nonfluoroscopic technology with electroanatomical mapping using the CARTO mapping/ablation system has shown promising results in defining the arrhythmia circuit, facilitating diagnosis, and guiding ablative therapy. Based on our preliminary experience, a systematic approach to postoperative IART using electroanatomical mapping is described. Further studies are needed to fully evaluate the impact of this new technology on the management and therapy of IART.