Background Idiopathic nephrotic syndrome (INS) is the most frequent glomerular disease in childhood, with an incidence of 2-4 cases per 100,000 children. Currently, all children with INS are treated at onset with steroids. Approximately 80% of cases respond to oral corticosteroid therapy, but 75-80% of these children will experience relapses which can recur over many years. The optimal duration and dosage of steroid therapy at onset and during subsequent relapses is debated. For each patient, the challenge is to minimise potential side effects of steroid therapy (hypertension, bone disease, Cushing syndrome, obesity, growth retardation, cataracts and a variety of psychological, social and behavioural disturbances) while achieving a good clinical response. This is particularly difficult at the beginning of the illness, because of the lack of reliable indicators that allow the identification of patients who will respond poorly or will experience frequent relapses. In 2006 the Cochrane Collaboration published the first systematic review of corticosteroid therapy for childhood idiopathic nephrotic syndrome. They concluded that children with the first episode of steroid sensitive INS should be treated for a minimum of three months, to achieve a reduction in the subsequent relapse rate.