Congenital lymphatic and vascular malformations and infantile hemangiomas can be combined under the heading of endothelial malformations. Based on their biologic behavior, endothelial malformations can be divided into two groups: infantile hemangiomas and vascular malformations. Vascular malformations can be subdivided into lymphatic, capillary, venous, and arteriovenous malformations. Often frightening for the patient and the patient's family, some endothelial malformations, however, will resolve; yet others can lead to long-term disfigurement and even can be fatal-due to airway obstruction, secondary infection, or exsanguination. When recognized early, however, the appropriate therapy, or watchful waiting, can be initiated, and the long-term physical and psychological consequences of these malformations can be minimized.