Spondyloepiphyseal dysplasia congenita (SED) is a rare form of skeletal systemic disease, characterized by congenital dwarfism with a short trunk and epiphysial dysplasia in the long bones and vertebral bodies. Patients also frequently saffer from atlanto-axial instability due to os odontoideum. Compression of the spinal cord caused by atlanto-axial instability is a common, serious complication in SED patients, and causes severe spinal cord symptoms or occasionally sudden death. We present an SED patient who underwent a posterior fusion of the occiput to the cervical spine for severe spinal cord symptoms due to atlanto-axial instability.