Myocarditis contributes to the global burden of cardiovascular disease primarily through sudden death and dilated cardiomyopathy, and the contribution of myocarditis as a cause of sudden death is most likely underestimated. For example, in Japan, the rate of myocarditis was estimated from an unselected national registry of 377,841 autopsies. 434 of these cases (0.11% or about 1:1000) had idiopathic, interstitial, viral, or non-specific myocarditis. In contrast, the rate of myocarditis was 3% (six of 200) in autopsies of sudden death patients in Japan. However, of 97 (77 male, 20 female) school children who experienced sudden death in Kanagawa prefecture, 3 of the 18 (16.6%) with histologically established cardiovascular disease had myocarditis. The majority, 60 of the 97 children, had acute heart failure of unknown etiology. Many of these children would likely have had myocarditis if a sensitive and specific noninvasive diagnostic test to identify myocarditis was available. Furthermore, systematic evaluation by cardiac autopsy would likely increase the rate of myocarditis diagnosis is children with sudden death.