Twenty cases of ependymomas of the intradural filum terminale in adults have been reviewed. Their pathology was quite uniform, of a myxopapillary type, similar to the low grade ependymoma described by Kernohan, which represent about 23% of the tumours of cauda equina. Mean age of the patients was 35.7 years. Mean time between the first symptom and the diagnosis was 46 months. Clinical symptoms were often non specific, with low back pain and radiculalgias. At the time of operation, clinical signs were essentially motor deficits usually moderate (11 cases), sphincter disturbances (10 cases), and sensory loss (9 cases). In 3 patients with rapid worsening, an intratumoral haemorrhage was found. In 2 other cases, intracranial hypertension was the main symptom: in the first, it was related to hydrocephalus probably caused by spinal subarachnoid haemorrhage; in the second, there was no ventricular dilatation. In this series, neuroradiological examinations had consisted mainly in myelographies. C.T. scan has been performed in 3 patients; in only one case it has allowed to visualize a presacral extension. One patient had preoperative M.R.I.: the association of an expansive lesion with upper cyst in conus medullaris and presence of blood in the sacral area permitted the diagnosis of ependymoma of the filum terminalis. The average size of the tumours was 8 cm. Total removal has been possible in 15 cases (and in 2 of the 5 giant tumours), subtotal removal in 2 cases, and partial removal in 3 cases. In 4 patients where existed an intraspinal cord extension above the conus, it has been resected completely, except for one case with recurrence. Patients with a total removal had a good functional recovery (13/15). No recurrence has been observed in this group. In conclusion, with M.R.I., one may hope an earlier diagnosis, condition of radical surgery. So, radiotherapy which is not without risk, could be avoided.