Cardiomyopathy is a leading cause of death in patients with Duchenne muscular dystrophy. Congestive heart failure is often sub-clinical and unrecognized as a result of the severe physical limitations of this patient population. We report the case of a 16-year-old boy with Duchenne muscular dystrophy who demonstrated normal left ventricular systolic function at rest by screening transthoracic echocardiogram. This patient, however, was noted to have depressed left ventricular contractile reserve by dobutamine stress echocardiography. Dobutamine stress echocardiography can have an important role in unmasking subclinical heart failure in this patient population.