Human enteroviruses (HEV) are an important cause of myocarditis and are associated with the pathogenesis of dilated cardiomyopathy (DCM). Current polymerase chain reaction studies in human myocardium have provided evidence that HEV are present in acute and chronic myocarditis as well as in DCM. To our knowledge, the presence of the HEV genome in the myocardium of human patients with heart failure (HF) after myocardial infarction (MI) has not been reported, nor have HEV been implicated as a factor affecting HF progression in patients after MI. Information about the presence of HEV in the heart tissue seems to be clinically important, since HEV infection is a frequent cause of HF and increased mortality. We present the case of a 54-year-old woman with a history of MI and HF progression. Our investigations suggested HEV as a possible cause of HF progression. Successful treatment with interferon- improved the patient's clinical status, apparently confirming our hypothesis.