Duchenne Muscular Dystrophy (DMD) severely impacts heart health. Decreasing LV ejection fraction (EF) is a late and highly variable outcome in this cohort. Earlier indications of cardiac involvement would improve patient management and provide insight into the utility of emerging therapy. Boys with DMD (N=25) and healthy volunteers (N=8) underwent cardiac MRI exams including short-axis tagged images. EF, peak LV twist, and peak mid-wall circumferential strain (Ecc) were estimated. Ecc and twist were significantly reduced in patients (9.3°±4.3° vs. 14.8°±3.6°, p< 0.004) and (-15.8±5.8% vs. -18.5±3.2%, p<0.02). Whereas, EF was not significantly different between groups. ~50% of DMD patients with normal EF had reduced twist and Ecc. Reduced peak LV twist and mid-wall Ecc measured by MR tagging may be earlier and more sensitive indicators of cardiac involvement in boys with DMD.