Idiopathic nephrotic syndrome is a rare kidney disease characterised by nephrotic proteinuria, hypoalbuminemia, hyperlipidaemia and oedema. The incidence of idiopathic nephrotic syndrome ranges from 2 to 7 cases per 100,000 children per year. Children between 1 and 10 years of age are mainly affected. The pathogenesis is associated with damage to the microstructure of glomerular filtration barrier, which may be caused by a variety of immune-mediated factors. Circulating factors such as hemopexin, cathepsin, soluble form of urokinase plasminogen activator receptor may be responsible for proteinuria in idiopathic nephrotic syndrome. Another possible cause of nephrotic proteinuria is dysregulation of T cells, including regulatory T cells and B cells. Nephrotic proteinuria occurs in other diseases that are associated with pathological action of lymphocytes, such as immunodysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX syndrome), and Hodgkin’s lymphoma. Numerous relapses of proteinuria in idiopathic nephrotic syndrome may be associated with latent Epstein–Barr virus infection via antigenic mimicry. Relapses of proteinuria may also occur in response to gluten or allergens in patients with coeliac disease or food allergy. Idiopathic nephrotic syndrome is managed with immunosuppressants. They inhibit immune system activity, which consequently allows for reaching and maintaining remission of the disease.