 Glutamine inhibits whole body protein degradation in children with Duchenne Muscular Dystrophy DMD. The effect is observed after 5 h oral glutamine administration and is also found when glutamine is given over a 10-day period. This multi-site national study aims to evaluate the functional benefit of long-term oral glutamine administration in 30 DMD children using a randomized double-blind placebo-controlled cross-over design. The study includes two 4-month periods: 1 a treatment period in which the subject receives oral glutamine 0.5 gkgd and 2 a control period in which the subject receives a placebo. The order of treatment allocation is randomized. The two 4-month periods are separated by a 1 month wash-out period. The children are monitored every 2 months during period 1 M0, M2, M4 and period 2 M5, M7, M9 in the clinical investigation centres of Hospital Robert Debré in Paris and the CHRU de Lille, as well as the clinical research centre of the CHU de Poitiers. Evidence of a functional benefit would involve evaluating the administration of glutamine over longer periods as early as possible following diagnosis among severely handicapped children and in other chronic pathologies associated with increased muscle protein catabolism. In DMD, such evidence would enable children to undergo gene therapy under improved physical condition. 