Only 6 cases arising on the eleventh cranial nerve have been reported in the world literature. The case of an 51-year-ald woman with spinal accessory neurilemmoma is presented. A cystic mass at the valecular region, which is associated with hydrocephalus, was demonstrated on computed tomogragh scan. The tumor was totally removed. The spinal accessory nerve root was confirmed through suboccipital craniectomy. It is benign and mortality appears quite low.