Among the research conducted under the Health Labour Sciences Research Grant Program by the study group on ossification of spinal ligaments, we reviewed studies on patients with ossification of the posterior longitudinal ligament (OPLL) with regard to methods for assessing their QOL as well as the study results. Methods for assessing QOL included the use of a single question, health-related QOL scales such as the SF-36 and SF-8, and the QOL criteria used in the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) . In patients with OPLL, which is a condition characterized by pain and numbness that primarily affects the patient's lifestyle rather than survival, the degree of pain was strongly related to QOL. Among activities of daily living, transferring and bathing were strongly related to QOL. Therefore, it is important to maintain appropriate rehabilitation.