An animal model of dilated cardiomyopathy following encephalomyocarditis (EMC) virus has been developed. Virus was isolated from mouse hearts and viral antigens were detected in the myocardium until the second week of infection, but neither was found thereafter. Differences were found among different strains of mice in the frequency of occurrence and severity of myocarditis, and even in the character of the pathologic lesions. Thus, genetic factors may play an important role in the pathogenesis. Autoantibodies against heart developed and the distribution of cardiac myosin isoenzymes was altered during the course of myocarditis. Virus, vaccine, maternal vaccination, recombinant interferon alpha A/D and ribavirin were effective in protecting the mice from developing myocarditis. This animal model is suitable for studying the pathogenesis of viral myocarditis and evaluating preventive and therapeutic interventions of the condition.