The authors report a case of cerebral aneurysm in an 8-year-old boy with Klippel-Trenaunay-Weber syndrome. This syndrome is a type of neurocutaneous disorder characterized by skin hemangiomas and hypertrophy of soft tissues and/or osseous structures in the involved region. Spinal hemangioma is occasionally found in this syndrome and may cause spinal subarachnoid hemorrhage. To our knowledge, however, no case of cerebral aneurysm in a child with this syndrome has been reported previously in the literature.