A simple and precise classification has been established during a ten-year international cooperation. There are two major groups: hemangiomas, always regressive; and vascular malformations, which never regress; they grow, throughout life, to varying degrees. Management of vascular malformations has been clearly defined. Capillary malformations do not require examination, unless they are associated with other anomalies, such as hypertrophic underlying bone, or the leptomeningeal vascular anomaly of the Sturge-Weber syndrome. Venous type malformations are diffuse, and consist of entirely anomalous channels, with low flow. CT scan and MRI clearly demonstrate the extent of tissue involvement in venous malformations; for these slow-flow malformations the evaluation is performed without resorting to invasive diagnostic techniques: phlebography is rarely performed, and arteriography is unnecessary. Arteriovenous malformations are dangerous high-flow vascular malformations, leading to skin ischemic necrosis, and congestive cardiac failure. Arteriography shows enlarged tortuous arteries, with arteriovenous shunting, and early venous drainage. CT scan and MRI show the deep components of the lesions. Doppler ultrasound evaluation is used to follow the course of the disease.