Clinical and cellular differences between hemangiomas and vascular malformations in children have been defined. Hemangiomas are benign endothelial cell neoplasms that appear in infancy and usually have a natural history of proliferation and involution. Vascular malformations are errors of vascular morphogenesis that are present at birth, grow with the child, and never involute but often expand. The authors reviewed the preoperative angiograms of 14 children who had cellular analyses of resected vascular lesions. Hemangiomas could be distinguished from vascular malformations by the presence of a well circumscribed mass demonstrating intense tissue staining, usually organized in a lobular pattern. The vascular malformations, although angiographically variable depending on the predominant vascular channel type, were diffuse lesions consisting entirely of vessels without intervening tissue stain. These angiographic differences between hemangiomas and vascular malformations corroborate clinical and laboratory studies.