The gross blood supply and intrinsic vascular anatomy of the facial nerve in the temporal bone are described, and their significance is discussed. At the vertical part of the facial nerve, the stylomastoid artery lies on its anteromedial side as far as the upper third of the nerve. The artery then loops around the lateral or medial side of the nerve, and divides into several branches. At the convex aspect of the genu, these branches anastomose with one another to form an arterial network, passing to the horizontal part. The petrosal branch of the middle meningeal artery reaches the geniculate ganglion and forms a profuse, fine arterial network. The main arterial trunk extends toward the second bend in the nerve, but it never reaches the vertical part. Studies on the draining veins are also described. Duplication of blood vessels from different sources was seen at the horizontal part of the nerve. This would suggest a special vulnerability of this area to vascular injury, since in our topographical study of Bell's palsy within two weeks of its onset, 72 out of 117 cases (61.5%) were found to have suprastapedial lesions.