We describe a case of duplication of the left internal carotid artery
from a point 1 cm distal to the origin to the proximal petrous segment
where the vessel reunites. Duplication and fenestration of the intern
al carotid artery are discussed. A review of embryologic development i
s presented. Identification of these entities is important, especially
in patients who require surgical intervention involving the internal
carotid artery.