Objective: In this study, we aim to determine demographic features and laboratory data of Turkish children who are diagnosedwith acute rheumatic carditis and to evaluate echocardiographic indices of the left ventricle (LV) and right ventricle (RV) systolic-diastolic functions at the time of diagnosis.Methods: This is a retrospective review of 100 children who were hospitalized because of the diagnosis of acute rheumatic fever(ARF)-related acute-stage carditis and 100 healthy children who were matched with respect to age and body mass index. All subjects initially underwent detailed two-dimensional (2D), pulsed Doppler, and tissue Doppler for assessment of ventricular functions.Results: Internal diameter of LV, measured during end-systole, was significantly increased and the mitral annular plane systolicexcursion was decreased in patients compared with those in controls (p=0.005). Although E’ velocity derived from septal mitralannulus were significantly lower, isovolumetric contraction time and myocardial performance index were increased in the carditisgroup compared with that in the control group. Peak early diastolic (E’), late diastolic (A’), and systolic (S’) myocardial velocities; isovolumetric contraction time; and myocardial performance index measured from the tricuspid annulus were similar in the carditisand control groups, although isovolumetric relaxation time was significantly prolonged. The carditis group had significantly lowermean corpuscular and platelet volume than the control group, although erythrocyte sedimentation rate and serum C-reactiveprotein levels were higher.Conclusion: We detected a subclinical reduction in the systolic and diastolic function of both ventricles in children with the first attack ofARF. “Pulsed” and tissue Doppler techniques in pediatric patients with ARF have an important role in assessing cardiac functions.