Since calcification or ossification of the posterior longitudinal ligament of the spine was first described in Japan in 1960 by Tsukimoto, Teryama used the term of OPLL (Ossification of Posterior Longitudinal Ligament) in 1964 and mainly reported in Japanes. But recently, the incidence of the OPLL has been reported increasing among the non-Japanese. Because of the OPLL may be associated with severe neurologic symptoms, which need to have surgical decompression, exact diagnosis and analysis are necessary. The OPLL can be diagnosed by simple spine, conventional tomography, myelography and CT. Authors analysed radiologic findings of the OPLL in 8 patients, who were diagnosed by simple spine, conventional tomography, myelography and CT, and then performed spinal operation, at Hanyang University Hospital from March 1980 to June 1983. The results were as followings : 1. The age range was between 45 and 63 years and most prevalent age was 6th decades (63%). 2. All of the patients were male. 3. All of the OPLL occurred in the cervical spine and predominant at the level of C3,4 (48%). 4. The most common length of the OPLL was 2 vertebral level. 5. Except one, which was discontinuous at the level of disc space, all of the OPLL were continuous in length. 6. 7 of 8 OPLL were located in the midine, but one was in right. 7. The OPLL seemed to correlate with spondylotic changes. 8. Of all diagnostic procedure, CT provided better and exact visualization of the lesion with axial scan and sagittal reconstruction.