Thirty-six children with Down syndrome, between two-and-one-half and 13 years of age, were evaluated for instability of the cervical spine, in order to determine the prevalence of upper cervical spine instability in Saudi children with this condition. Nine patients exhibited abnormal cervical spine: movement. Eight;patients had atlanto-occipital instability and three had atlanto-axial instability. None of the nine patients with abnormal cervical spine movements developed any neurological deficit. Our survey confirms the data from the literature that there is a high incidence of cervical spine instability in children with Down syndrome.