OBJECTIVES: The purpose of this study was to establish the incidence of and risk factors for sudden cardiac death (SCD) in pediatric dilated cardiomyopathy (DCM). BACKGROUND: The incidence of SCD in children with DCM is unknown. The ability to predict patients at high risk of SCD will help to define who may benefit most from implantable cardioverter-defibrillators. METHODS: The cohort was 1,803 children in the PCMR (Pediatric Cardiomyopathy Registry) with a diagnosis of DCM from 1990 to 2009. Cumulative incidence competing-risks event rates were estimated. We achieved risk stratification using Classification and Regression Tree methodology. RESULTS: The 5-year incidence rates were 29% for heart transplantation, 12.1% non-SCD, 4.0% death from unknown cause, and 2.4% for SCD. Of 280 deaths, 35 were SCD, and the cause was unknown for 56. The 5-year incidence rate for SCD incorporating a subset of the unknown deaths is 3%. Patients receiving antiarrhythmic medication were at higher risk of SCD (hazard ratio: 3.0, 95% confidence interval: 1.1 to 8.3, p = 0.025). A risk stratification model based on most recent echocardiographic values had 86% sensitivity and 57% specificity. Thirty of 35 SCDs occurred in patients who met all these criteria: left ventricular (LV) end-systolic dimension z-score >2.6, age at diagnosis younger than 14.3 years, and the LV posterior wall thickness to end-diastolic dimension ratio <0.14. Sex, ethnicity, cause of DCM, and family history were not associated with SCD. CONCLUSIONS: The 5-year incidence rate of SCD in children with DCM is 3%. A risk stratification rule (86% sensitivity) included age at diagnosis younger than 14.3 years, LV dilation, and LV posterior wall thinning. Patients who consistently meet these criteria should be considered for implantable cardioverter-defibrillator placement. (Pediatric Cardiomyopathy Registry; NCT00005391).