During the clinical course of dilated cardiomyopathy, arrhythmias, thromboembolism and sudden death are common and may occur at any stage. In patients with dilated cardiomyopathy, elevated plasma levels of tumor necrosis factor-α are associated with poor prognosis. In animal experiments and clinical trials, myocardial tumor necrosis factor-α expression correlates with increased mortality rates. A case of sudden death of a previously asymptomatic young man, having a definitive autoptic diagnosis of dilated cardiomyopathy with endomyoelastofibrosis, is presented. We investigated the cardiac morphology and the expression of tumor necrosis factor-α in cardiac tissue specimens to elucidate the role of tumor necrosis factor-α expression in this fatal case. Our results demonstrate a strong positive myocytes reaction for tumor necrosis factor-α in the heart specimens. The pathogenesis of the fatal event is discussed with particular reference to the histological findings and myocytes expression of tumor necrosis factor-α.