Large facial hemangiomas can have associated central nervous system malformations, particularly the Dandy-Walker posterior fossa malformations. Abnormal arteries, especially those of the central nervous system, coarctation of the aorta, cardiac defects, and unusual ophthalmologic abnormalities can also occur. We describe two patients with large facial hemangioma, congenital cataracts, and structural arterial abnormalities, particularly of the central nervous system vasculature. One of these infants also had a Dandy-Walker malformation detected on prenatal ultrasound at 12 weeks' gestation, suggesting that this syndrome had its origin during the first trimester of pregnancy. This infant also had a lingual thyroid and developed symptomatic hypothyroidism, possible induced by interferon alfa therapy of her hemangioma. These cases are discussed, along with 41 previously reported cases with similar findings. Large facial hemangiomas may have a distinctive group of associated arterial, central nervous system, and ophthalmologic anomalies. We propose the acronym PHACE syndrome to emphasize the characteristic findings of this neurocutaneous syndrome: posterior fossa malformations, hemangiomas, arterial anomalies, coarctation of the aorta and cardiac defects, and eye abnormalities.