The aim of this study was to evaluate the long-term effects in young children with Duchenne dystrophy of an intermittent low dosage regime of prednisolone (0.75 mg/kg per day for 10 days per month, or 10 days on and 10 days off). Six children under 5 years with Duchenne dystrophy have been commenced on this schedule, four of whom have been followed for at least 30 months and are reported here. All four presented with classical Duchenne dystrophy, and had an out-of-frame deletion in the Duchenne gene and absence of dystrophin in their muscle. All four showed a rapid and dramatic response in muscle function and strength. In three of the four there was an almost complete remission of all clinical signs of dystrophy. Their functional scores remained well above the average scores recorded in untreated Duchenne boys at the same age. There was no increase in weight, stunting of growth, decreased bone density or any other significant side effects related to the prednisolone. Our current experience suggests that this intermittent, low-dosage prednisolone regime is well tolerated and can be safely given long-term in young children with Duchenne dystrophy. The striking response also suggests that there may be an optimal window for treatment of Duchenne dystrophy in the early stages of the disease.