Primary neoplasms of the central nervous system have been rarely reported in sheep. A three-year-old Rasa Aragonesa ewe was admitted to the small ruminant external consultancy at the Veterinary Faculty of University of Zaragoza, Spain. Clinical, haematological and neurological examinations were performed. Neurological examination showed signs of ataxia, hyperextension of the right front limb and abnormal postural reactions. The animal was unable to stand and walk, even with help. Patellar and flexor reflexes were normal and superficial sensation was present but decreased. Humanitarian sacrifice was carried out one month later. Gross and histopathological findings revealed a choroid plexus papilloma located in the fourth ventricle of the brain. To the authors’ knowledge this is the first description of this neoplastic disorder in sheep.