Aim: The incidence of myocarditis in children is uncertain because patients with minor symptoms can remain undiagnosed. We hypothesized that screening all children who are hospitalized for an acute infection with troponin-I (TnI) would reveal myocarditis cases and performed a prospective screening study. Methods: Between October 2005 and July 2008, a blood sample for TnI measurement was taken every time a sample for C-reactive protein measurement was drawn. If TnI value was above the screening limit (0.06 mug/L), electrocardiogram (ECG) and cardiac ultrasound were performed. TnI measurements were repeated until at normal level. Results: Altogether, 1009 children were screened during the 33 months. TnI was above the screening limit (0.06 mug/L) in six children. None of them had any signs of myocarditis in ECG or cardiac ultrasound. Five of those six children were younger than 30 days. All had a respiratory infection as a cause for hospitalization, three of which was caused by RSV. In four children, all younger than 30 days, TnI levels remained high (>0.37 mug/L) for two months, but decreased after that to normal levels. Conclusion: The incidence of myocarditis during viral infections is low and a routine TnI screening for asymptomatic myocarditis is not useful.