Duchenne muscular dystrophy (DMD) is a progressive, degenerative neuromuscular disease caused by gene mutations that result in the absence or deficiency of dystrophin protein. Absence of dystrophin compromises the regenerative ability of muscle fibers, and, as muscle deterioration overtakes muscle growth, loss of upper limb function causes difficulties in performing daily activities and negatively impacts quality of life. Eteplirsen (Exondys 51; Sarepta Therapeutics, Cambridge, MA), the first FDA approved treatment for DMD in the US, is indicated for treatment of patients with DMD amenable to exon 51 skipping. Eteplirsen has not been approved for marketing outside of the United States. We evaluated long-term upper limb function outcomes in patients aged 7–13 years with DMD amenable to exon 51 skipping who participated in 2 eteplirsen clinical trials. Study 201, a 28-week trial, randomized patients to receive once-weekly intravenous eteplirsen infusions (30 mg/kg, n = 4; 50 mg/kg, n = 4) or placebo (n = 4) for 24 weeks. At week 25, all patients received open-label eteplirsen through week 28. In study 202, an open-label trial, all patients received once-weekly eteplirsen at the same dose as in study 201 through 240 weeks. Upper limb function tests included the 9-Hole Peg Test (seconds), a maximum voluntary isometric contraction test (MVICT) with a Quantitative Movement Assessment system to assess elbow flexion and extension and hand grip (kg). Study 201 enrolled 12 patients; all completed extension study 202. Following confirmation of dystrophin production, patients showed relative stability or minimal decline of upper limb function on all measures assessed through week 240. In conclusion, eteplirsen may slow the deterioration of upper arm function in patients with DMD amenable to exon 51 skipping.