The article presents results of electrophysiological study of the function of the ureter in the frequency range of 0.6-35 Hz, conducted in 100 children aged 5 to 13 years with chronic pyelonephritis. Data of 35 healthy people were used as a control. It was shown that the features of ureter contractions were significantly different in the two groups. Marked decrease of amplitudes of signal harmonics was found at a frequency of 1.4 Hz in patients with pyelonephritis compared to controls. Myostimulation in pyelonephritis group has led to an approximation of harmonic amplitudes to the values of the control group.