Objectives: This study aims to evaluate the role of speckle tracking echocardiography (STE) to identify myocardial deformation abnormalities in acute rheumatic fever. Methods: Twenty-seven patients and twenty-seven healthy children were studied prospectively. The patients were divided into two subgroups as moderate/severe carditis and mild/no carditis according to valve involvement. The left ventricular global longitudinal strain (LVGLS) and strain rate (LVGLSR), left ventricular global circumferential strain (LVGCS) and strain rate (LVGCSR), and right ventricular global longitudinal strain (RVGLS) and strain rate (RVGLSR) were examined by STE. Results: Left ventricular global longitudinal strain, LVGLSR, LVGCS, LVGCSR, RVGLS and RVGLSR were significantly lower in patients in acute phase of disease than controls. There were no differences in strain and strain rates between patient subgroups before treatment. After acute phase, statistically significant improvements were found in LVGLS, LVGLSR, LVGCSR values of the patients with moderate/severe carditis and LVGLS, LVGCS, LVGCSR, RVGLS, RVGLSR values of the patients with mild/no carditis. The strain parameters of the patients and controls did not differ significantly after the treatment. Conclusions: In acute phase of rheumatic heart disease, patients have reduced left and right ventricular strain and strain rates, which shows improvements after treatment.