Background: Re-establisment of Fontan circulation by eliminating the drawbacks of classic Fontan modifications has been proposed recently to improve the functional class and quality of life of patients with failed Fontan circulation. Methods: Five patients underwent extracardiac and lateral tunnel Fontan conversion due to failure of the Fontan circulation, after classic Fontan modifications. All of the patients were female and mean age was 10.2 +/- 2.2 years (range: 8 - 14 years). Previous Fontan modifications were atriopulmonary anastomosis in 3 and Kawashima operation in 2 patients. Time to re-operation for Fontan conversion was 6 +/- 1.5 years (range: 4 - 8 years). indications for re-operation were right heart failure, right atrial dilatation, and intractable atrial arrhythmias in patients with previous atriopulmonary anastomosis, progressive hypoxia and exercise intolerance in patients with previous Kawashima operation due to pulmonary arteriovenous fistulas. Previous atriopulmonary anastomoses were converted to intra-atrial or lateral tunnel Fontan operation with modified right atrial Maze procedure. Extracardiac Fontan completion was carried out after previous Kawashima operations by redirection of hepatic veins to the lungs. Results: There was no mortality and no major morbidity. All patients were discharged from the hospital in good condition and in sinus rhythm. No prolonged or recurrent effusions were observed. On follow-up, all patients were in sinus rhythm and had NYHA class I functional capacity. In two Kawashima patients, SPO2 gradually increased from 60% to 90% six months after the operation. Discussion: We suggest that Fontan conversion should be considered in patients with previous atriopulmonary anastomosis, when right atrial dilatation or intractable atrial arrhythmias with deteriorating functional status develops. Redirection of hepatic venous flow to lungs induces regression of pulmonary arteriovenous fistulas and improves arterial saturation in patients with previous Kawashima operation.