Stroke affects up to 13 of 100,000 children, is more common in boys and African Americans, and is associated with considerable cognitive and psychiatric morbidity, as well as motor disability. Around half are hemorrhagic and half are ischemic. Underlying conditions include sickle cell disease, cardiac abnormalities, chromosomal abnormalities (eg, Down syndrome), and neurocutaneous conditions (eg, neurofibromatosis), but up to half the patients with ischemic stroke have no previously diagnosed condition. Although there is almost certainly an important genetic component to stroke risk, head trauma, infections, drugs and radiation appear to play an etiological role in some patients. The majority of the patients with infarction in an arterial distribution have associated cerebrovascular disease. Vascular pathologies include carotid or vertebrobasilar dissection, intracranial vasculopathy affecting the middle and anterior cerebral arteries, which is often transient, and moyamoya. Intermediate risk factors may include hypertension, hypoxia, and poor nutrition leading, for example, to iron deficiency and hyperhomocysteinemia. Some chronic conditions may directly influence the child's behavior and stroke recurrence risk, although large cohorts and randomized controlled trials will be needed before strategies for modification can be evidence-based.