Nonterminal myelocystocele is a rare type of spinal dysraphism characterized by a closed defect with an underlying CSF-filled cyst, either contiguous with the central spinal canal or attached to the spinal cord by a fibrovascular stalk. The authors report the unusual case of a neonate with a prenatal diagnosis of cervicothoracic nonterminal myelocystocele who underwent postnatal surgical untethering of the lesion. Pathological analysis of the excised lesion revealed neuroglial tissue with an ependymal lining associated with a mature teratoma. Three months after surgery, the patient has normal lower-extremity sensorimotor function and no evidence of bowel or bladder dysfunction. To the best of the authors' knowledge, this is the first report of a patient with a nonterminal myelocystocele found to have an associated mature teratoma.