A case of trigeminal neurinoma with marked extracranial extension is reported with a review of the literature. A 60-year-old female noticed numbness over the left side of the face during the proceeding 15 years. Two years prior to admission, she began to complain of itching and lancinating pain at the left lateral aspect of the nose. Neurologic examination on admission revealed diminished corneal reflex on the left side and hypesthesia in the distribution of the left trigeminal nerve. There was no weakness or atrophy of the ipsilateral masticatory muscles. The remaining cranial nerves and cerebellar functions were normal. Craniograms showed destruction of the left petrous apex, enlargement of the left superior orbital fissure and an extensive bone defect in the floor of the left middle cranial fossa. CT disclosed a huge heterogeneously enhancing mass lesion in the left middle cranial fossa, which extended posteriorly into the left cerebellopontine angle and inferiorly into the pterygoid and infratemporal fossae. Cerebral angiograms revealed medial displacement of the left internal cerebral artery in the ganglionic, cavernous and supraclinoid portions, and elevation of the left middle cerebral artery in the sphenoidal portion. Although the left meningohypophyseal trunk was dilated, no tumor stain was observed. A transantral biopsy specimen provided the diagnosis of neurinoma with Antoni type A tissue. The patient was followed up at the outpatient clinic as radical operations were not agreed upon. Eight cases of trigeminal neurinoma with extracranial extension are reviewed including the presented case. There were two males and six females, and the age varied from 16 to 65 years.(ABSTRACT TRUNCATED AT 250 WORDS)