Hemangiomas are the most frequent tumors found in newborns, but mostly regress by the age of 7. Spontaneous progression and such complications as hemorrhage, disseminated intravascular coagulation (Kasabach-Merritt syndrome), threatened cardiovascular decompensation, and threatened interference with vital functions are rare and must be treated. Embolization therapy is a new therapeutic approach: vascular malformations and hemangiomas with pronounced arteriovenous shunts are treated by selective arterial embolization of the most peripheral branches of the supplying blood vessels. In contrast, lesions with a steady, slow blood perfusion can be treated by direct embolization of the cavernous system; further thrombosis and organization of the thrombus may lead to a permanent and complete occlusion of the hemangioma. If permanent occlusion cannot be achieved, temporary or partial thrombosis may allow curative plastic or reconstructive surgery, which would otherwise be impossible.