he majority of children with idiopathic nephrotic syndrome haveminimal change nephrotic syndrome, but 10% have mesangio-proliferative glomerulonephritis or focal and segmental glomeru-lonephritis . The response to corticosteroids is highly predictiveof histology, with 93% of children with minimal change nephroticsyndrome achieving remission following an 8-week course ofprednisone . Between 25 and 50% of children with mesangio-proliferative glomerulonephritis or focal and segmental glomeru-lonephritis on biopsy also responded to prednisone [2,3]. Childrenwith idiopathic nephrotic syndrome are now classified accord-ing to their initial response to corticosteroids as having eithersteroid-sensitive nephrotic syndrome (SSNS) or steroid-resistantnephrotic syndrome, as the majority are steroid sensitive and do not undergo renal biopsy at diagnosis.Of children with SSNS, 75–90% will have one or more relapses,and about half will relapse frequently or become steroid dependent[4,5]. The majority will continue to respond to corticosteroidsthroughout their subsequent disease course [4–6], and the long-term prognosis for complete resolution with normal renal functionis good. In the International Study of Kidney Disease in Children(ISKDC), the proportion of children without relapse reached 80%by 8 years of follow-up . About 10% of patients overall [7,8] and30–40% of patients with steroid-dependent or frequently relapsingSSNS will continue to relapse as adults [6,9].In children with SSNS, the aim of corticosteroid therapy is toinduce and then maintain remission while minimizing adverseeffects. Corticosteroid-sparing agents are used to achieve pro-longed remissions in children with frequently relapsing or steroid-dependent disease who have significant adverse effects from pred-nisone therapy. In this chapter the current evidence base for cor-ticosteroid therapy and corticosteroid-sparing agents in children with SSNS will be reviewed.