Idiopathic nephrotic syndrome is the most common glomerular disease in children, with a prevalence of 1.15–16.9 cases per 100,000 children per year worldwide. In some cases, nephrotic syndrome has a frequently relapsing course or dependence on steroid therapy is formed, which leads to the appointment of immunosuppressive therapy. So far, in clinical practice, there is no unambiguous approach among physicians to the management of patients with nephrotic syndrome, especially when it comes to the further choice of immunosuppressive therapy. Because of the serious side effects of long-term corticosteroid use, doctors prescribe steroid adjuvants to maintain remission and limit the cumulative effect of glucocorticosteroids. Among adjuvants, mycophenolate mofetil, with mycophenolic acid as the active ingredient, is believed to be the most preferred option due to fewer adverse events, acceptable tolerability and, at the same time, high efficacy. This article describes the advantages and features of the use of mycophenolic acid in clinical practice, provides data on pharmacodynamics and drug monitoring, and discusses issues of personalized medicine.