In 2019, the first multi-source registry of sudden cardiac arrest and death for patients aged 1-50 years launched in Victoria, Australia. Sudden cardiac arrest (SCA) affects approximately fifteen hundred younger Victorians per year. The End Unexplained Cardiac Death (EndUCD) Registry enrols SCA/death (D) cases aged 1-50 years, providing family screening, access to psychological support through clinical sites and creating a genetic biorepository for whole-genome sequencing. The registry will support clear pathways of cardiac assessment, epidemiological profiling and routine family screening and psychological support.