Aims To evaluate paediatric relatives of first- and non-first-degree family victims with a history of premature sudden cardiac death (SCD) or aborted cardiac arrest (ACA). Methods and results Thirty-six consecutive referred families after SCD (n = 29) or ACA (n = 7) of a family member were analysed. Referral was either due to an inherited heart disease identified after autopsy, post-event, or family evaluation (n = 20 families) or due to sudden unexplained death (SUD, n = 16 families). In 3 of 16 (19%) SUD families, an inherited heart disease was diagnosed by evaluation of the paediatric relatives. In 5 of 25 (20%) referred paediatric relatives of SUD families, an inherited heart disease was identified, mainly sinus node dysfunction (n = 3). A total of 13 of 33 (39%) referred paediatric relatives of families with known inherited heart disease were affected, mainly with cardiomyopathy (n = 5) and primary electrical disease (n = 7). Prevention of SCD was initiated in 16 of the affected children by implantation of an antibradycardia device (n = 3), an implantable cardioverter defibrillator (ICD, n = 6), and/or antiarrhythmic medication (n = 8). Appropriate and successful ICD discharges occurred in four. Conclusion A stepwise, comprehensive clinical investigation of SCD or ACA families identifies a substantial number of paediatric relatives at risk of SCD. This allows for targeted prevention by effective treatments and evaluation of further relatives.