A 51-year-old woman became unconscious 19 hours after the onset of a headache. Computerized tomography disclosed an intracerebral hematoma in the left temporal lobe, with ventricular penetration. Antiography demonstrated the characteristic appearance of cerebrovascular moyamoya disease as well as an aneurysm-like shadow in the left temporal lobe, which proved on histological examination to be a pseudoaneurysm.