The extradural lumbosacral localization represents for ependymomas an exceptional event full of interest both from an etiopathogenetic point of view and from a clinical one. Extradural ependymomas develop in two characteristic sites: with an anterior or presacral expression in the retro-rectal pelvic area; posterior in the intergluteal space below the lumbo-sacral fascia. The possibilities of a correct diagnosis are based essentially on radiographical examinations and CAT which supply useful factors, but not peculiar to the lesion. The Authors describe a case of posterior "extradural lumbo-sacral ependymomas" which is added to the 36 already reported.