Although isolated hypogastric artery aneurysms are among the rarest of all aortoiliac aneurysms, they are among the most devastating. Two cases, one with rupture directly into the urinary bladder, are presented and the typical clinical triad of compressive symptoms, pelvic mass, and previous aneurysm is described. Intraoperative management is predicated upon sac obliteration with minimal tissue dissection. An aggressive approach to asymptomatic or minimally symptomatic aneurysms is urged due to the very high mortality following rupture.