Fibrous dysplasia of the cranial air sinuses is rarely reported in the literature. This is the first report of frontal lobe abscess (FLA) associated with fibrous dysplasia of the frontal sinus (FDFS). A 29-year-old female presented with seizures and acute confusion. Cranial computed tomography (CT) revealed fibrous dysplasia of the left frontal sinus and associated FLA. She was referred to the neurosurgical service and the abscess and dysplastic tissue were removed. Histological examination confirmed fibrous dysplasia. We review the radiological appearance of FDFS with FLA. Clinicians should be aware of the association between these two conditions. (C) 2004 Elsevier Ltd. All rights reserved.