The authors report a rare case with arteriovenous fistula (AVF) at V3 portion of the left vertebral artery with spontaneous regression. A 33-year-old woman came to our hospital complaining of a headache. She showed no neurologic abnormality but a vascular bruit was noted on her left mastoid region. Angiography revealed the AVF at the left vertebral artery emptying into the surrounding venous system. Little steal phenomenon was noted from the contralateral vertebral artery, although the filling of the basilar artery from the left vertebral artery was poor. Subsequently she was observed without any interventional treatment for 2 months until the follow-up angiography was performed, which revealed spontaneous regression of the AVF with residual arterial pouch at the orifice of the AVF.