The mechanisms of pathogenesis of myocarditis have remained elusive. Despite the demonstration a decade ago that persistent viral infection of the myocardium occurred in many patients, a clear description of the pathologic progression has not been forthcoming. Over the past year, a number of studies have added to the data defining the crucial roles of cytokine expression in the myocardium and the aberrant induction of apoptosis. Further, a mouse model of myocarditis resulting from the myocardial expression of tumor necrosis factor-alpha has been described. In addition, the identification of the common coxsackievirus B and adenovirus receptor has offered an explanation for the puzzling observation that these highly distinct virus types both cause cardiac disease. Finally, the near-eradication of endocardial fibroelastosis associated with persistent mumps virus infection by vaccination supports the notion that coxsackievirus B and adenovirus vaccines may help reduce the incidence of myocarditis.