BACKGROUND: After sudden death occurs in the young, first-degree family members should undergo clinical screening for occult cardiac disease, but the diagnostic yield from screening is not well-defined in the United States. OBJECTIVES: The purpose of this study was to determine the clinical predictors of cardiac diagnosis in children referred for evaluation following a sudden death in the family. METHODS: Patients referred for a family history of sudden death were evaluated in a retrospective review from a tertiary pediatric referral center. RESULTS: Among 419 pediatric relatives of 256 decedents, 27% of patients were diagnosed with a disease or had a clinical finding of uncertain significance. Patients were diagnosed with heritable cardiac disease in 39 cases (9.3%). Nonheritable cardiac disease was diagnosed in another 5.5% of patients. Clinical findings of uncertain significance were present in 52 patients (12.4%), including abnormal electrophysiological test results (41 of 52) or imaging test results (11 of 52). Among patients diagnosed with a heritable cardiac disease, the nearest affected relative was almost always a first-degree relative (37 of 39, 95%). The strongest predictors for a successful diagnosis in the patient were an abnormal electrocardiogram and a first-degree relationship to the nearest affected relative (odds ratios: 24.2 and 18.8, respectively). CONCLUSIONS: Children referred for a family history of sudden death receive cardiac disease diagnoses (14%), but clinical findings of uncertain significance increase the challenge of clinical management. The importance of a diagnosis in first-degree affected relatives supports the clinical practice of testing intervening family members first when patients are second- or higher-degree relatives to the decedent.