Background: The experience with uretero-arterial fistulas has been limited. However, the aggressive treatment of pelvic tumors with surgical resection and radiotherapy, along with liberal use of ureteral catheters, has been attributed to an increase in their incidence. Unless they are promptly diagnosed and treated, uretero-arterial fistulas are associated with considerably high rates of morbidity and mortality. Urologists need maintain a high degree of suspicion for uretero-arterial fistula in high-risk patients. We herein present the clinical course of an iliac artery-uretero-colonic fistula. Case Presentation: A 67-year-old woman with a history of colon cancer who underwent laparoscopic high anterior resection in July 2010. A ureteral stent inserted to right ureteral stricture, which developed as a result of local recurrence of the tumor in September 2010. She had undergone chemoradiotherapy, but the lesion had slowly increased in size. During the replacement of the ureteral stent in April 2016, she immediately experienced bladder tamponade, bloody bowel discharge, and hypotension. Contrast CT revealed a complex fistula between the right distal ureter and the right internal iliac artery. Furthermore, contrast medium flowed into the intestinal tract through the tumor. The patient was therefore diagnosed with internal iliac artery-uretero-colonic fistula. Arteriography revealed a right uretero-internal iliac artery fistula, and the embolization of the right internal iliac artery was performed. The right ureteral stent was removed. Her hematuria and bloody bowel discharge disappeared, but right nephrostomy was performed because she presented with acute pyelonephritis to ureteral obstruction. Conclusion: In the present case, the uretero-arterial fistula was caused by the long use of an indwelling stent, chemoradiotherapy, infection, and an increase in the size of the lesion. When a suspected uretero-arterial fistula is accompanied by bloody bowel discharge, we should consider the possibility of traffic to the intestinal tract.