Pulmonary arteriovenous malformations occur in 15-20% of patients with Rendu-Osler-Weber syndrome and can be the source of paradoxical emboli caus ing cerebral ischemia, septic emboli leading to brain abscesses, or polycythemia causing hyperviscosity and cerebral ischemia. The diagnosis of these malforma tions may be elusive, since classic clinical or radiologic findings may be absent in some patients. The authors report a patient with Rendu-Osler-Weber syndrome with cerebral ischemia who had normal findings from a pulmonary examina tion and chest roentgenogram. An ultrafast computed tomography scan of the chest demonstrated, however, a pulmonary arteriovenous malformation in the right upper lobe that was successfully resected. Ultrafast computed tomography of the chest is a relatively noninvasive method of screening for a pulmonary ar teriovenous malformation in a patient with Rendu-Osler-Weber syndrome and otherwise unexplained neurologic symptoms.