Forecasting the prognosis of a child when diagnosed with Ebstein's anomaly is difficult. We, therefore, studied which factors at the time of diagnosis are associated with death during childhood. All consecutive patients (0-18 years) diagnosed with Ebstein's anomaly in the Netherlands between 1980 and 2014 were included. Survival curves were obtained using the Kaplan-Meier method. By using the Cox proportional hazard model, we analysed the factors (at diagnosis) that were associated with death. We included 176 patients. Thirty-one patients (18%) died before the age of 18 years. The 1-year survival was 84% and remained stable at 82% from 35 months after diagnosis and onwards. Modified Ross Heart Failure Class 4 at the time of diagnosis was the most important risk factor for death during childhood (HR 12.5, 95% CI 4.4 to 35.9). Furthermore, diagnosis in the neonatal period (HR 4.2, 95% CI 1.5 to 12.0), severe tricuspid valve regurgitation (HR 2.4, 95% CI 1.2 to 5.0), severe right ventricular outflow tract obstruction (HR 3.7, 95% CI 1.8 to 7.7) and a patent ductus arteriosus (HR 2.8, 95% CI 1.3 to 6.0) at the time of diagnosis were univariately associated with death. Multivariable analysis showed that presentation with Heart Failure Class 4 and a ventricular septal defect is the strongest predictor of death in childhood and adolescence. Patients with Ebstein's anomaly presenting with Heart Failure Class 4 and a ventricular septal defect have a high risk of death during childhood.