This report examines a case involving a huge cystic cervical neurinoma existing extra- and intramedullary. The histogenesis of intramedullary neurinoma, pathohistogenesis of large intratumoral cyst are discussed. The role of Magnetic Resonance Imaging (MRI) in the diagnosis of spinal tumors is also discussed. A 23-year-old male was admitted to our ward or having tetraparesis. On admission, spastic tetraparesis and sensory disturbance below level C 2 were noticed. Electrophysiological examinations suggested a left-dominant intraspinal lesion. Conventional radiological examinations revealed widened cervical spinal canal, swelling of the spinal cord at level C 6-7, left extramedullary mass at level C 5, and a complete block at level C 4. MRI disclosed intramedullary tumor existing from the medulla oblongata to the lower cervical including macrocysts, and an extramedullary tumor on the left at level C 3-5. Surgical exploration was made and both of intra- and extramedullary tumors were confirmed to be neurinoma. The postoperative course was favourable. The patient was able to walk with aids, and was referred to the rehabilitation center 6 months after the operation. In histological investigations, the major components of the tumors were typically Antoni-A type neurinoma, and an abundant hemosiderin deposits. There were many hyalinized whorling portions around the cysts. Though spinal neurinoma is the most common spinal tumor, the intramedullary neurinoma is extremely rare. Only 31 cases have been reported as far as we could investigated. The histogenesis of this type of lesion is still unsettled.(ABSTRACT TRUNCATED AT 250 WORDS)