The authors encountered a patient with an anomalous external carotid-vertebral anastomosis, which was found incidentally during examination for a recurrent pituitary adenoma. Left carotid angiography demonstrated a muscular branch of the ascending pharyngeal artery feeding the left vertebral artery, while bilateral retrograde vertebral angiography failed to demonstrate the origins of either vertebral artery. To our knowledge, this is the first documented case of ascending pharyngealvertebral anastomosis associated with the bilateral absence of vertebral arteries at their origins.