Abstract only Introduction: Patients with congenital heart disease (CHD) may require cardiac transplantation for either primary management or failed surgical palliation. This study describes 1-year mortality of patients with CHD listed for transplant, trends in 1-year mortality over three decades, and use of mechanical support in this population. Methods: The United Network for Organ Sharing database was queried to identify patients aged 0-30 years with CHD listed for transplant from 1990 to 2019. VAD status at listing and 1-year mortality after listing were examined using the Cochran-Armitage trend test. Results: Overall, 9327 patients with CHD aged 0-30 years were listed for transplant between 1990 and 2019 with a total 1-year mortality rate of 26% (n=2466). For non-survivors to 1-year after listing, 66% (n=1619) died before transplant and 34% (n=847) after transplant. Patients <1 year of age were the most frequent age group listed for transplant (n=3678, 39%) and experienced the highest 1-year mortality after listing (n=1264, 34%). The 1-year overall mortality decreased over the study period (1990-1999: 33% vs 2000-2009: 30% vs 2010-2019: 19%, p<0.0001), including in infants <1 year of age (1990-1999: 41% vs 2000-2009: 37% vs 2010-2019: 26%, p<0.0001). Overall, few patients were supported with VAD at listing (3.1%). However, VAD use increased (1990-1999: 1.0% vs 2000-2009: 2.8% vs 2010-2019: 5.0%, p< 0.0001) and the 1-year mortality for patients with VAD at listing decreased over time (1990-1999: 57% vs 2000-2009: 35% vs 2010-2019: 20%, p<0.0001). Conclusions: Survival after listing for heart transplant is improving, however mortality amongst infants remains high. While there has been >50% improvement in survival in patients of all ages with CHD supported with a VAD at listing, VADs are used rarely in patients with CHD. Further study is needed to understand which patients may benefit from mechanical circulatory support, especially among infants.