Urinary undiversion is an accepted technique in a highly selective patient population. We reconstructed the urinary tract in six female mongrel dogs. A 15 cm. segment of ileum was isolated, both ends were closed and bowel continuity re-established. The proximal two-thirds of each ureter were anastomosed to the proximal end of the ileal segment. The distal one-third right ureteral segment, in continuity with the bladder, was anastomosed end-to-side to the distal ileal segment. Information from the intravenous pyelograms, renal function tests, electrolytes and pathological studies showed normal upper tracts without dilatation or obstruction, preservation of renal function and normal electrolytes except for mild hyperchloremia in all 6 animals. There was chronic pyelonephritis in one animal and mild focal renal inflammation in two animals. The uretero-ileal anastomoses were patent and the ureters were not dilated. The interposed ileum functions well as a conduit and does not become a reservoir over time. We believe incorporating ileum into the urinary tract in this technique of undiversion is a safe and effective clinical alternative in selected patients.