Congenital renal arteriovenous malformations are rare. Moreover, rupture of congenital arteriovenous malformations in the unilateral renal agenesis with uterine malformation is more rare. We present a case of acute urinary retention due to large hematoma of spontaneously ruptured congenital arteriovenous malformation of unilateral renal agenesis in a 33-years-old woman.