Although anterior spinal decompression and fusion (ASF) serves as the established surgical method for cervical spondylotic myelopathy and cervical disc herniation, there are some cases requiring re-operation because of disorders in adjacent segments over long-term. At our institution thirty-six cases underwent laminoplasty after ASF. Twenty-five cases of them were caused by disorders in the adjacent segments. The risk factors of these disorders in the adjacent segments of ASF evaluated were number of segments of fusion, diameter of spinal canal, presence of stenosis except for fusion segments in the first operation, pre-operative Japanese Orthopaedic Association cervical myelopathy score, pre and post operative cervical alignment. There were no significant differences in all subjects. Although ASF has a high risk of re-operation compared with posterior surgery in the first operation, it also has certain merits. Posterior surgery is not considered superior to anterior surgery only in terms of lower rate of re-operation. We could not identify the risk factors of disorders in the adjacent segments of ASF in this study.