An internal urinary diversion of the upper urinary tract was planned in 107 patients with acute, stone-related or chronic tumor-induced ureteral obstruction. Acute ureteral obstruction (n = 34, group I): in 30 of 32 cases (94.1%), successful placement of an indwelling stent resulted in complete drainage in 28 of 30 patients (93.7%). In 2 cases, no satisfactory urine diversion was possible, despite several catheter changes and confirmed clearway through the installed catheters. Chronic ureteral obstruction (n = 73, group II): successful placement of the indwelling stent was possible in 63 of 73 (86.3%) cases. Complete urine diversion was achieved in only 25 patients (39.7%). Hydronephrosis was diminished in 28 patients (44.4%) and persisted or increased in 10 cases (15.9%), despite orthotopic positioning of the catheter and numerous stent changes. Complete urine drainage was achieved with an internal urine diversion in only 4 of 10 cases with chronic hydronephrosis. It is assumed that the reason for the high failure rate lies in the catheter construction and, with respect to chronic hydronephrosis, the reduced or non-existent contractility of the upper urinary tract in combination with the inevitable pressure connection between the upper and lower urinary tract.