Anomalous arterial supply to the temporal and occipital lobes was studied retrospectively in 320 patients with 640 bilateral carotid angiograms. An unusual artery arising from the supraclinoid part of the internal carotid artery was identified in seven angiograms (six patients). Proximally, this artery takes the same course as the cisternal segment of the anterior choroidal artery, gives rise to the choroidal branch to the choroid plexus of the lateral ventricle, and then supplies the medial and inferior parts of the temporal and occipital lobes. It was concluded that this artery represents anomalous development of the anterior choroidal artery, having large temporal and occipital branches that supply the medial and inferior parts of the temporal and occipital lobes.