Ureteral motility changes were followed up in 10 patients with hydronephrosis and urolithiasis which were recorded by multichannel impedance ureterography prior to internal drainage and during stent manipulations. The establishment of the ureteral stents reduces peristaltic amplitude and frequency as well as ureteral tonicity. After the stent removal 20% of the examinees showed peristaltic hyperfunction of the ureter. Urodynamic positive effects of the stents consist in better regulation of the motility, elimination of its local disturbance foci, improved coordination of movements of different parts of the upper urinary tracts. For positive results it is important to practice an individual approach to choice of drainage time and stent size. Urodynamic impedance studies can be used in control of endoscopic treatment adequacy.