Background. Children with CAKUT-syndrome (congenital malformations of the urinary tract) quickly develop an inflammatory process, which, in combination with dysplasia and/or urodynamic disorders, creates a high risk of developing early chronic renal failure. Purpose of the study: to identify the main factors of the formation, features of the clinical course of nephropathies, morphometric parameters and features of the organ blood flow of the kidneys in young children against the background of CAKUT syndrome. Methods. Study design: It carried out a cohort prospective study. The main group included 26 children with pyelonephritis against the background of CAKUT syndrome at the age from zero to 36 months of life, the comparison group consisted of 29 children with non-obstructive pyelonephritis of the same age. It carried out a comparative analysis of antenatal and postnatal anamnesis, clinical, laboratory and instrumental data in the considered groups of children with nephro-urological pathology. Additionally, it researches the morphometric parameters of the kidneys and the Doppler indices of the renal vessels. The research conducted during 2016-2018. Results. In children with a chronic course of nephropathy in combination with CAKUT-syndrome, possible predictors of an early onset of the disease are: anemia, damage to the urinary tract with pathological urinary syndrome during pregnancy and a combination with defects of this system in the woman herself, and the development of placental insufficiency. In the group with CAKUT syndrome, a decrease in renal filtration function (in 88.5% of children) and persistent trace proteinuria (in 65.4% of children) are recorded by the end of the first year of life. According to ultrasound, in addition to signs of obstructive nephropathy, it recorded decreases in the thickness of the parenchyma and a violation of organ hemodynamics with an increase in the resistance index. In the observed group of children, CAKUT syndrome combined in 100% of cases with connective tissue dysplasia syndrome also. Conclusion. Thus, CAKUT syndrome leads to early realization of nephropathies in children with a rapid decline in renal function.