Objective: Extracorporeal membrane oxygenation remains the mainstay of mechanical circulatory support initiation and maintenance in children with cardiac insufficiency. However, the outcomes after prolonged extracorporeal membrane oxygenation for cardiac insufficiency in children remain ill defined. Methods: We reviewed the International Extracorporeal Life Support Organization data from January 1, 2000, through December 31, 2011. We defined prolonged extracorporeal membrane oxygenation as uninterrupted support for >= 14 days. Results: A total of 777 children aged <18 years required extracorporeal membrane oxygenation support for >= 14 days. Of these, 176 (23%) survived to hospital discharge. Compared with the nonsurvivors, the survivors were older (median age, 0.64 vs 0.10 years; P < .01), weighed more (median weight, 7.0 kg; range, 2-90; vs median, 4.0; range, 1.4-100 kg; P < .01), had a shorter duration of support (mean, 20 +/- 6 vs 22 +/- 9 days; P < .01), and a fewer number of organ system complications (mean, 2.8 +/- 1.7 vs 3.6 +/- 1.6, P < .01). Children with congenital heart disease had worse survival than those with cardiomyopathy and myocarditis (15% vs 42% and 52%, respectively; P < .01), and those with 1-ventricle physiology had worse survival than those with 2-ventricle physiology (10% vs 18%, P = .01). Seven percent (n = 56) reached cardiac transplantation, with 66% surviving to hospital discharge versus 19% of those not transplanted (P < .01). Conclusions: The attrition is high after prolonged extracorporeal membrane oxygenation support for cardiac insufficiency in children. Cardiac transplantation in this cohort was rarely achieved and was associated with high mortality compared with benchmarks for cardiac transplantation survival. Earlier redirection of care or conversion to other modes of mechanical support as a bridge to transplantation should be considered.