Two uncommon but important cerebrovascular manifestations of human immunodeficiency virus (HIV) infection in children are arteritis with formation of fusiform aneurysms and arterial sclerosis with vascular occlusion. We studied the CT and MR imaging features of HIV in two girls and one boy (9 to 18 years old) and compared them with autopsy findings in two patients. One of the children had findings consistent with small areas of subacute infarction and the other two had fusiform dilatation of the major vessels of the circle of Willis. The ischemic lesions and arteriopathy were confirmed at autopsy. In one patient, an incidental B-cell lymphoma (not visible on the imaging studies) was diagnosed.