We conducted a retrospective study of children with lumbosacral lipomas treated in the Department of Pediatric Neurosurgery hospital Timone Enfants in the last 20 years. We selected patients with lipomas of the conus medullaris who underwent preventive surgery. 86 ,4 % of the patients remained asymptomatic during the follow-up. Worse results were observed in children older than one year old at surgery with transitional lipoma, with the conus medullaris was below L5 and when the resection had been partial. In view of the results, the authors recommend the preventive surgery before the first year of life under neurophysiologic monitoring in order to perform a total near-total resection with a neural plate reconstitution.