Purpose: This study was done to investigate the effect of exercise on functional capacity of patients with Duchenne muscular dystrophy (DMD) with progressive muscle weakness. Material and methods: This study was carried out on 22 patients with DMD diagnosis. Patients were evaluated at 1., 3. and 6. months and were followed with a home program. Their body weights, range of motion, base of support, functional status, manual muscle tests scores of 9 muscles in lower extremity, 10 m. walking and fast walking and independence in walking activity were assessed. Results: Although muscle strength and time required to perform an activity were protected; increase in body weight, limitation of ankle dorsiflexion and support surface were found statically meaningful in the 6 months period (p<0,05). Discussion: Although the muscle strength and time activity performance were stable, the walking parameters were influenced from the prognosis of the disorder.