The clinical outcome of 18 patients, who presented with a Coxsackie virus myopericarditis in 1965, was evaluated 23 years later. Five patients had died, two of them had had heart failure. Thirteen patients and 23 healthy control subjects underwent exercise testing with gas exchange analysis. Left ventricular (LV) peak filling rate (PFR) was estimated by digitized M-mode echocardiography. Left ventricular ejection fraction was measured at rest and during exercise by radionuclide angiography. All patients were free of cardiac symptoms. Their clinical examination and the chest X-ray were normal. Peak oxygen consumption was not decreased in the patient group compared with the control group. PFR was significantly lower in the patient group than in the control group, 10.2 +/- 0.4 vs 13.2 +/- 0.4 cm s-1, P less than 0.001 (mean +/- SEM). LV ejection fraction was normal at rest in all patients (58 +/- 1%). An abnormal LV ejection fraction response to exercise was observed in two patients. Our data indicate that long-term prognosis after acute Coxsackie virus myopericarditis is good in a majority of patients.