Background: An arteriovenous fistula in the female pelvis is a rare finding. We report a pelvic arteriovenous fistula diagnosed antepartum. Case: At 38 weeks' gestation, a 32-year-old woman, gravida 3, para 1, was found on bimanual examination to have a pulsating mass on the left vaginal sidewall. Magnetic resonance imaging revealed a tangle of arteries feeding into an aneurysmal dilation of a branch vein of the left internal lilac, extending to the left lateral wall of the cervix and vagina, and ending in a large varix in the lateral wall of the vagina. The patient was asymptomatic and underwent primary cesarean delivery of a healthy female infant. Twice during her postpartum course, she underwent angiography and embolization of extensive left- and right-sided feeding vessels. Five to 6 weeks after each embolization, the vaginal mass recurred. Conclusion: A pelvic arteriovenous malformation diagnosed antepartum presents a dilemma in regards to risk of hemorrhage, congestive heart failure, and successful ablation.