The primary objective of this study is the assessment of the safety of an intramuscular administration of rAAVrh74.MCK.micro-Dystrophin to the Extensor Digitorum Brevis (EDB) muscle of patients with Duchenne Muscular Dystrophy (DMD). Safety will be assessed by changes in hematology, serum chemistry, urinalysis, immunologic response to rAAVrh74 and micro-Dystrophin protein, and reported history and observations of symptoms. Subjects will be evaluated at baseline, injection visit (days 0-2), and return for follow up visits on days 7, 14, 30,60, 90, and 180 and at the end of 1st and 2nd years. On Day 180, subjects will undergo a muscle biopsy on the injected muscles in one foot compared with placebo-treatment in the opposite foot to establish transgene expression and any potential toxicity from gene transfer.