Background: In young patients (aged 12 years) with Duchenne muscular dystrophy (DMD), cardiac systolic function is generally described to be within the normal range. We aimed to determine whether two-dimensional speckle tracking echocardiography (STE) or tissue Doppler imaging (TDI) could detect left ventricular (LV) subclinical myocardial dysfunction in young patients with DMD. Methods: Thirteen pediatric patients (mean age 9.69 ± 2.2 years) with DMD and 26 age-matched healthy children (mean age 9.65 ± 2.2 years) were studied. All subjects were examined by conventional echocardiography, TDI, and STE. Standard echocardiographic measurements of left ventricular (LV) systolic and diastolic function were performed. Myocardial velocities including peak systolic and early and late diastolic myocardial velocities were calculated in the longitudinal direction in the interventricular septum by TDI. Speckle tracking analyses were performed by acquiring apical four-, three-, and two chamber views with the highest possible frame rates. Results: Conventional parameters were similar between the two groups, except for higher heart rates in patients with DMD compared with controls. The results of TDI examining LV diastolic function showed that annular peak velocity during early diastole (e`; 10.9 ± 1.7 vs. 14.6 ± 1.7 cm/s), e`/a` ratio (2.0 ± 0.5 vs. 3.0 ± 0.5), E/e` ratio (9.4 ± 1.4 vs. 7.3 ± 0.8) and myocardial performance index (0.46 ± 0.05 vs. 0.36 ± 0.06) of the mitral septal annulus among DMD patients differed significantly from those of healthy children. Significant decrease in global longitudinal systolic strain was found in patients with DMD (-16.6 ± 3.7 vs. -21.2 ± 2.1), markedly in the LV basal inferolateral and basal inferior walls. Conclusion: In young patients with DMD who have global normal systolic function, reductions in systolic deformation parameters as well as reduced early diastolic myocardial velocities can be detected especially in the basal inferolateral LV walls. The prognostic significance of these findings warrants further longitudinal follow-up.