Uretero-vascular fistulae are rare. As compared to aortic, uretero-iliac fistulae are by far more frequent according to a 1:8 ratio. We present one case of uretero-prosthetic fistula in a man operated upon the resection of an aortobisiliac aneurysm and Dacron prosthetic graft; six years later, a blunt trauma to the body was followed by a threatening shock, resistant to medical measures. Two subsequent emergency operations allowed to a difficult diagnosis and a life-saving repair of the fistula. Some hypotheses on the pathogenesis of the condition are discussed as well as its clinical problems.