Steroids may have a beneficial effect on the course of Duchenne muscular dystrophy (DMD). However, results vary in different studies. This study consisted of 66 DMD boys who were in the therapy group and 22 DMD boys in the control group. The mean ages were 6.8 ± 2.1 years (range 2.5-12.5) and 7.0 ± 1.3 years (range 5.0-9.0), respectively. We assessed muscle strength, 10-m walking, ankle contracture, and loss of independent walking ability age and onset of scoliosis. Treatment regimen was oral prednisolone 0.75 mg/kg on alternate days, plus vitamin D 600-1200 units/day and a calcium-enriched diet. After a follow-up period of 2.75 ± 1.1 years (range 1.5-5) and when compared with controls, there was a statistically significant change in muscle strength between the two groups after 12 months (P < 0.05). Although 10-m walking time decreased in therapy group (P < 0.05), there was not significance between the groups in the end. Boys in the control group developed significantly less ankle contractures (P < 0.05). None of the therapy group had scoliosis during the follow-up period (mean age 10.8 ± 1.2 years), whereas seven boys of the control group had scoliosis at a mean age of 11.7 ± 2 years. Loss of walking ability age was statistically different between groups (P < 0.05). Our results indicate that, alternate-day prednisolone regimen may prolong ambulation and scoliosis can be delayed or prevented.