Introduction. Timely diagnosis of various forms of pyelonephritis in children requires special attention and knowledge concerning clear clinical and laboratory criteria, since pyelonephritis tends to become chronic and contributes to the formation of chronic renal failure. The aim of the review is to establish the leading factors of formation, diagnosis, and prognosis determining the features of the course and outcomes of pyelonephritis in children. Pubmed, Google Scholar, Medline, and eLIBRARY.RU databases were used in the review. Pyelonephritis has been established to be a variant of endogenous infection caused by opportunistic bacteria that can live in the body for a long time and lead to infection only under certain conditions. Hematogenous and direct invasion is relatively rare. The clinical picture of pyelonephritis in children is quite diverse and depends on various factors. Given that insufficiently examined patients have a high risk of chronization of the course of the disease with the subsequent formation of foci of nephrosclerosis, an accurate diagnosis of the location of lesions in pyelonephritis is necessary. After receiving urine test data, determining biomarkers of the activity of the process and the presence of clinical manifestations of pyelonephritis in children, it is necessary to immediately prescribe empirical antibacterial therapy with prior urine culture and mandatory determination of antibiotic resistance, which will significantly reduce the risks of complications and nephrosclerosis.