80 cases of urinary diversions by means of an ileal or colon conduit are reported. Indications and the operative technique with several variations especially of the bowel-ureter-anastomosis are described. The significance of intestino-uretero-renal reflux and the role of urinary infection in different compartements of the isolated segment are discussed: if the stoma is large enough no reflux can be observed; in the majority of cases infection is limited to the distal part of the segment. Urinary diversion by isolated bowel segments seems to be a safe procedure especially for the protection of the upper urinary tract, preferable to diversion into the non-isolated colon.