Normal variations of the arteries and veins visualized during vertebral angiography of children were assessed by utilizihg measurements. The values were applied for evaluating dislocation and stretching of the vessels by brain tumors. Special emphasis has been placed on nodular and choroidal branches of the posterior inferior cerebellar artery, various measurements of the posterior fossa veins and the choroid vein of the lateral ventricle. These were considerably useful for the diagnosis of brain tumors in children. Because of minimal vascular changes associated with posterior fossa tumors, it has been emphasized that two or more findings should be evaluated together for arriving at a correct diagnosis.