Despite pathologic evidence of myocardial inflammation, the significance of myocarditis in children with acute rheumatic carditis remains controversial. Elevations in cardiac troponin I have been demonstrated in other forms of myocarditis. The purpose of our study was to determine if levels of cardiac troponin I are elevated, suggesting myocardial injury, in patients with acute rheumatic carditis. We identified all those patients with acute rheumatic fever, presenting between July 1998 and December 2000, who had clinical evidence of carditis, such as a new murmur of mitral or aortic regurgitation, and who had an echocardiogram, measurements of levels of cardiac troponin I, erythrocyte sedimentation rate, and/or C-reactive protein performed at the time of presentation. Their charts were reviewed for demographic and clinical data. Echocardiograms were reviewed for severity of aortic and mitral regurgitation, and measurements made of left ventricular ejection fraction, fractional shortening, and end-diastolic dimension. We found 16 patients with acute rheumatic carditis, ranging in age from 2.0 to 16.1 years, with just over one-third having symptoms of congestive heart failure. All patients had evidence of acute inflammation. There was a significant relationship between symptoms and severity of mitral regurgitation. No patient had elevated levels of cardiac troponin I level. The fact that levels of cardiac troponin I are not elevated in the serum of children with acute rheumatic carditis suggests that there is minimal myocytic necrosis in this setting. This supports the concept that acute valvar regurgitation is the major hemodynamic abnormality in these patients.