PURPOSE: To clarify risk factors for the development of myelopathy in patients with cervical spondylotic cord compression. METHOD: The authors reviewed articles in which risk factors for the development of myelopathy in patients with cervical spondylotic cord compression were discussed. Ossification of the posterior longitudinal ligament (OPLL) was also reviewed as a disease which causes cervical cord compression to clarify pathomechanism of the development of myelopathy. RESULTS: Cervical motion segment disorders are considered to be multifactorial, and developmental size of the canal and foramina, pathological encroachment, biomechanical effects, and circulatory deficiencies are always present to some degree. Static and dynamic factors should be considered for the development of myelopathy. To clarify the pathomechanism of the development of myelopathy in patients with cervical spondylotic spinal cord compression, the exact natural history of CSM should be understood. CONCLUSION: Several predictable risk factors for the development of myelopathy have been proposed in CSM or OPLL studies, but they were not definitive. Further prospective population-based study is needed to clarify the mechanism.