There was a development of the diagnostic aids such as electromyography, discography, epidural venography, myelography, and CT in lumbar disc herniation. In 1984, Edgardo et al. described that the diagnosis of unusual extreme lateral disc herniation might be suggested by CT, but the diagnosis was made more certain with CT done after discography. Also, in 1986, Michael et al. reported,that the addition of CT to lumbar discography could help the clinician to obtain an anatomically valid diagnosis in people who, in spite of prior negative diagnosis evaluation, continue with significant clinical symptoms of low back pain and sciatica. The authors have studied 25 cases of CT after discography from July 1984 to June 1987. The results were as follows;1) CT after discography, which was a diagnostic method of direct visualization of nucleus pulposus herniation, shown same finding as previous CT in 16 cases and more accurate finding of herniated site snd size in 2 cases. 2) In one csse, the diagnosis of extreme lateral disc herniation, which was suggested by previous CT, made more certain with CT after discography. 3) There was false negative in 6 cases.