This article discusses the development and use of genomic predictors to define the population at risk for sudden cardiac death, which is usually defined as death from cardiac causes within an hour of symptom onset. The identification of genetic predictors of sudden death in heart failure is in its earliest stages. Mutations in ion channels have been shown to cause inherited forms of sudden death; there is, however, little evidence that mutations or rare single nucleotide polymorphisms (SNPs) in those genes are important causes of the common forms of sudden death. Other common variants in ion channels and related genes are associated with sudden death in the setting of acute myocardial infarction or heart failure. Ultimately, we hope to identify a handful of SNPs that modulate the risk of sudden death in heart failure and to develop an algorithm to predict risk based on genotype.