Enteroviruses are thought to be etiologic agents in some cases of human myocarditis and dilated cardiomyopathy. Murine models of acute coxsackievirus B3 myocarditis implicate coxsackie B viruses as possible causes of human myocarditis. Indirect evidence implicating enteroviruses as causative agents in human heart disease derives from serologic studies. More recently, direct evidence for enteroviral presence in diseased human heart tissues has been obtained by nucleic acid hybridization analyses. Although the data suggest that enteroviral infections may be associated with 18% to 50% of cases of myocarditis or dilated cardiomyopathy, or both, causality has not been established. Unanswered questions remain regarding the specific identity of the enteroviral genomes detected in the human heart and the potential for enteroviruses to persist in the heart.