Duchenne muscular dystrophy (DMD) is a fatal disease of progressive muscular weakness for which there is currently no effective treatment. The disease is caused by mutations in the gene for dystrophin. A subset of these mutations includes nonsense mutations, i.e., premature stop codons. Previous studies have shown that aminoglycosides are effective in allowing translation through stop codons. Recently, gentamicin was shown to restore functional dystrophin in a mouse model of DMD. The objective of this protocol is to determine if gentamicin is also an effective treatment in patients with DMD caused by nonsense mutations. This will be a preliminary, non-blinded study in which levels of intravenous gentamicin previously established to be safe, will be administered to identified patients meeting inclusion criteria over a two-week period. These patients will have CLIA approved laboratory documented stop codon mutations in the dystrophin gene. Quantitative dystrophin expression will be the primary outcome. Strength measurements will also be assessed before and immediately after the two-week treatment period. Follow-up evaluations will be made at one month. For this subset of patients with DMD it is anticipated that there will be a transient increase in dystrophin expression with a possible corresponding transient improvement in strength. Subsequent blinded studies to evaluate the most effective dose and dosing intervals would then be pursued.