The nephrotic syndrome is a clinical term and describes the finding of heavy and selective proteinuria leading to hypoproteinaemia and hypalbuminaemia. It is not a disease entity, but can be caused by various renal and systemic diseases. In children the most frequent renal type is the idiopathic nephrotic syndrome associated with minimal glomerular changes (minimal change nephrotic syndrome; MCNS). Focal segmental glomerulosclerosis and membranoproliferative glomerulonephritis are less frequent. Systemic diseases associated with nephrotic syndrome may be infectious, metabolic, toxic, malignant or autoimmune processes. The aetiology in most cases remains unknown. Managing children with nephrotic syndrome aims to diminish and abolish the massive proteinuria in order to eliminate the permanent risks associated with the nephrotic state, and to cure the renal process. This can be achieved best by identifying End eliminating the causative antigen, which however is only rarely possible. In the majority of cases, the physician should attempt to suppress the immunopathological processes by immunosuppressive agents. If these interventions fail, supportive treatment is important to decrease the pathological consequences of the disease. Most children with nephrotic syndrome suffer from MCNS and respond very well to corticosteroid treatment. The initial treatment with prednisone should be intensive and prolonged, which reduces the subsequent rate of relapses. A relapse should be treated with a standardised prednisone regimen in order to estimate the future course of the disease. If corticosteroid toxicity occurs, treatment with alkylating drugs (cyclophosphamide or chlorambucil) is indicated, which in the majority of cases is followed by a prolonged remission. If there are frequent relapses despite cytotoxic drug therapy, cyclosporin is the third immunosuppressive drug of choice, and is effective in corticosteroid-responsive nephrotic syndrome for as long as it is administered. All immunosuppressants have adverse effects, which should be recognised early by regular monitoring. In corticosteroid-unresponsive nephrotic syndrome, the type of disease determines the further immunosuppressive approach. Supportive treatment includes: diuretics to decrease massive oedema, prophylaxis and control of infections, control of hyperlipidaemia and replacement of metabolites lost in the urine.