A case with myopericarditis caused by type 3 ECHO virus was reported. The diagnosis was based on a significantly increased hemagglutination-inhibiting antibody titer (from 4:6 to 4:516) against type 3 ECHO virus in the acute and the convalescent phase. A 29-year-old male was hospitalized for chest pain and fever. The patient had congestive heart failure, pericardial effusion and temporarily appearing abnormal Q waves on his electrocardiogram in the acute phase all of which gradually improved within about 3 weeks. Cardiac catheterization performed on the 21st day of hospitalization disclosed normal coronary arteries, but a partially hypokinetic region was found in the left ventricular free wall. A right ventricular endomyocardial biopsy study revealed histological features of a small number of mononuclear cell infiltrations, myocardial cell necrosis and early fibrosis associated with an increased number of fibroblasts and ultrastructural changes including myocytolysis, vacuolation in sarcoplasm and dissociation of some intercalated discs. The endomyocardial biopsy study, and the electrocardiographic and cineangiographic findings in this case suggest that viral infection may induce clinical signs of myocardial infarction in the heart with normal coronary arteries.