Purpose of the work: to substantiate the choice and evaluate the effectiveness of the use of a metabolic therapeutic complex (vitamin E and L-carnitine) aimed at reducing tissue hypoxia and improving metabolic processes in the renal parenchyma during the treatment of acute pyelonephritis against the background of vesicoureteral reflux (VUR) as visceral manifestation of undifferentiated connective tissue dysplasia (UCTD) in young children. Materials and methods. Sixty-seven children aged 3 months to 3 years with pyelonephritis and VUR associated with UCTD were examined. The control group consisted of 65 young children with acute pyelonephritis, who after examination did not reveal VUR and signs of UCTD. The second control group included 40 somatically healthy children of the same age. In order to diagnose the presence of undifferentiated connective tissue dysplasia, all children with remission of the inflammatory process underwent a hydroxyproline urine test. Markers of renal parenchymal hypoxia were determined using a test for anticrystallization function of urine and daily urinary salt excretion according to the method of Yu.Ye. Veltyshchev and Ye.O. Yurieva. The markers of the morphofunctional state of the renal epithelial cytomembranes were studied by means of a test for calcification — the presence of polar lipids in urine, and a test for the presence of lipid peroxidation products (LPР) in urine. For young children with pyelonephritis, VUR and UCTD in whose urine a high excretion of hydroxyproline was detected, in addition to protocol treatment in the period of remission of the inflammatory process, it was recommended to take for a month medications that have antihypoxant properties and are able to improve metabolic processes in the renal parenchyma — vitamin E and L-carnitine in age-related doses. Results. The high frequency of detection of phenotypic signs of undifferentiated connective tissue dysplasia and significant urinary excretion of hydroxyproline (86.6 %) in children with pyelonephritis against the background of vesicoureteral reflux reliably indicate the presence of undifferentiated connective tissue dysplasia as a result of fibrillogenesis disorders. In young children with pyelonephritis against the background of vesicoureteral reflux, the presence of renal parenchymal hypoxia and nephrothelial membrane destruction was revealed, as indicated by a decrease in the anticrystallization function of urine, daily excretion of phosphates and a high excretion of lipid peroxidation products from urine and polar lipids. In children in whom the association of the pathological process with UCTD was detected, these changes were more significant. This is indicated by a more pronounce decrease, compared to children in whom no association with UCTD was found, in the anticrystallization function of urine, an increase in the oxalate excretion and a decrease in the daily urinary excretion of phosphates and urates, which was accompanied by a significant intensification of lipid peroxidation processes and the appearance of polar lipids in daily urine. After metabolic therapy with antihypoxant and membrane-protective action, the examined children showed a significant positive dynamics of the studied markers of tissue hypoxia and membrane destruction of the renal parenchyma. Conclusions. A positive effect of a metabolic complex (vitamin E and L-carnitine) during remission of the inflammatory process in the kidneys was revealed, which was expressed in a decrease in the degree of tissue hypoxia and membrane destruction, which confirms the possibility of reducing tissue hypoxia in children with pyelonephritis and vesicoureteral reflux associated with undifferentiated dysplasia connective tissue using vitamin E and L-carnitine in age-related doses for a month and allows you to recommend metabolite therapy to these children.