At hemodynamic evaluation in children with a hypertrophied unique kidney without signs of inflammatory process it was found that there is the increase in speed parameters of blood at vessels of all calibers at a normal resistive index. Distinctive hemodynamic changes in the unique kidney complicated with pyelonephritis, at absence of chronic renal insufficiency is increase in maximal systolic and minimal diastolic speeds of blood and also resistance index. Expressiveness of hemodynamic changes in patients with a unique kidney at presence of the urological pathology complicated with a pyelonephritis and chronic renal insufficiency depends on severity and duration of disease. At these patients intrarenal hemodynamic parameters have tendency to decrease in arteries of various caliber.