The cases of a child and an adolescent in whom internal-carotid-artery thrombosis followed non-penetrating trauma to the paratonsillar area from objects held in the mouth are reported, and are discussed together with 10 similar cases collected from the literature. Although the incidence of this complication of an accident almost unique to childhood is unknown, 2 out of 15 children in a consecutive series with acute hemiplegia had a history of such trauma. This suggests that specific inquiry concerning such injuries should be made in any child with an acute, focal neurologic lesion. Physicians seeing patients with paratonsillar injuries should be aware that neurologic complications may ensue. As a rule, there is a period of up to twenty-four hours from the time of injury to the onset of neurologic symptoms; this may cause confusion with an intracranial hematoma in patients with a history of prior or associated head injuries. The diagnosis of internal-carotid-artery occlusion can be proved clinically only by angiography, which should be performed before therapy is undertaken. One third of the children with internal-carotid-artery occlusion after intraoral trauma died; the constant pathological finding was extension of the thrombus distally into the major intracranial arteries, with massive infarction of the hemisphere. A theory of the pathogenesis of occlusion of the internal carotid artery after nonpenetrating trauma is presented. A plan of therapy based on this hypothesis is considered.