The Fontan operation has improved the survival of children born with single ventricle physiology. Selecting candidates for the Fontan operation may be difficult on borderline cases. No clear criterion has been established on the risk for staged Fontan palliation. Another aspect that remains controversial is the indications for fenestration. Intraoperative pulmonary flow study may identify high-risk patients for the procedure. In this report, the authors describe their results with Fontan procedures in children with pulmonary pressure >15 mmHg.