Prednisolone has been shown to improve strength in Duchenne dystrophy, the improvement starting within 10 days of treatment and reaching a maximum by 3 months, and then plateauing. Unfortunately this has been associated with an unacceptably high level of side effects. In an attempt to obtain the benefit of steroids without the side effects we devised an intermittent low dosage schedule, with 0.75 mg kg-1 day-1 for 10 days at the beginning of each calendar month. To date 32 boys with Duchenne dystrophy have been enrolled into an open randomized trial. Preliminary data show an influence on strength at 6 months but a slow decline at 12 and 18 months. The weight gain and other side effects have been much less than with continuous therapy.