Dermal sinus is a congenital lesion more frequently presented in the lumbar area. Produces tethering of the spinal cord and its presence increases the risk of infections of the CNS. The only treatment of those lesions should be neuro-chirurgical: the goal of the surgical procedure is to remove the lesion and to free the spinal cord from its attachment to the surrounding layers. Magnetic resonance is the ideal diagnostic procedure. We report two cases of children of ten months and one year old harboring a congenital dermal sinus complicated respectively with intramedullary and subdural abscess. Prompt surgical treatment allowed regression of the symptoms. The MR images are detailed.