BACKGROUND: Extracorporeal membrane oxygenation (ECMO) and cardiac transplantation are recognized to be expensive. METHODS: We performed a cost utility evaluation with a decision model approach, including 75 children with dilated cardiomyopathy. A cohort of patients with end stage heart failure who were offered ECMO bridging was compared with a similar cohort offered only conventional intensive care. Outcome was measured in cost per quality adjusted life year (QALY). RESULTS: Median follow-up was 4.39 years (interquartile range, 1.83-5.74 years), during which 50 children underwent transplantation, 16 had a period of recovery, and 25 died. ECMO bridging was highly effective (hazard ratio, 0.181; 95% confidence interval, 0.067-0.489; p = 0.001) but exceeded conventional criteria for cost-effectiveness. The reference incremental cost-effectiveness ratio (ICER) was pound65,645 per QALY and pound54,284 per life-year gained. Average life expectancy rose from 6.78 to 9.79 years and costs from pound146,398 to pound309,599 per patient with ECMO bridging. The ICER was sensitive to ECMO cost, the long-term transplant survival rate, and quality of life in transplant recipients. CONCLUSIONS: ECMO bridging is effective but expensive. The eligible target population is small, nationally, positively influencing affordability. We strongly support our national policy of mechanical bridge to transplant for suitable children in end stage heart failure. Cost effectiveness could be optimized by: 1) increased availability of organ donors, 2) reduction in mechanical support costs possibly by alternate devices and 3) inclusion of patients most likely to benefit.