Our ability to identify cerebrovascular lesions in children has improved in recent years and with it our willingness to consider the diagnosis of cerebrovascular disease in children. Magnetic resonance angiography and other tests have made diagnosis easier and safer, particularly in very young children and in patients with sickle cell disease. Transcranial Doppler examination makes it possible to accurately predict without angiography which patients with sickle cell disease are at most risk frr stroke. Many patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) syndrome have a specific mutation of the mitochondrial DNA, and soon the recently devised diagnostic criteria for MELAS syndrome may be replaced by molecular markers. There are many causes of cerebrovascular disease in children, and a thorough evaluation will discover a likely cause in about two thirds of the patients. Recent attention has focused on the HLA-B51 antigen and chicken pox as possible risk factors. Magnetic resonance imaging is also helpful in assessing the prognosis of children with cerebrovascular disease or head trauma.