Thirty-four patients with cervical cord tumor were followed in order to investigate the incidence of postoperative deformity or instability after laminectomies. Seven cases (20%) presented cervical instability, including three cases that required spinal fusion. Analysis of these cases revealed the identification of some risk factors that are involved in the pathogenetic mechanism of cervical instability, which are: age at operation, preoperative curvature in neutral position, number of removed laminas, C2 laminectomy, and destruction of facet joints. The number of these risk factors present in each case was shown to be directly related to the incidence of cervical instability. Patients who had not developed instability demonstrated 1.2 factors on average, while patients who had developed instability showed a mean of 2.5 factors. Patients who had additionally required spinal fusion presented 3 risk factors, including C2 laminectomy and destruction of facet joints.