Despite improved early results with the Norwood procedure (stage one palliation), patients remain with at-risk anatomy and interstage mortality continues to be a limitation of staged single ventricle palliation. Retrospective analyses have implicated residual or recurrent anatomic lesions as well as intercurrent illness as causes of interstage mortality. We hypothesized that potentially life-threatening anatomic lesions and illnesses would be manifest before serious physiologic impact by alteration in arterial saturation, failure to gain weight or in the case of dehydration, acute weight loss. As a result, we developed a home monitoring program of daily weights and oxygen saturations to earlier identify those patients at increased risk for interstage death. Frequent monitoring of these physiologic variables between stage one and two palliation identified life-threatening anatomic lesions and illness and permitted timely intervention that ultimately improved survival. All 36 survivors of the stage one palliation discharged from the hospital and entered into the home monitoring program survived the interstage period.