Low back pain and sciatica is one of the most frequent and troublesome problem in or thropedic field. There are many controversies about surgicsl procedure for the treatment of the patient with herniated nucleus pulposus. The advantages of anterior interbody fusion are through removal of remnsnt of the disc, restoration of disc height, correction of spinal alignment, preservation of posterior elements and neural component. The strut of ilisc bone was firmly impacted and patients could be mobilization earlier. It is well known that symptoms secondary to herniated nucleus pulposus can resolve after disc excision and anterior interbody fusion, but little has been written about regression of herniated nucleus pulposus. We analysed 20 cases in which serial C-T studies disclosed an unequivocal regression or complete disappearance of nucleus pulposus after anterior interbody fusion. The results were summerized as followings ; 1. Regression of herniated nucleus pulposus was average 2.65mm. 2. The clinical results were excellent in 20% of the patients, good in 60% and fair in 20% 3. The comparision are based on the finding at C-T, marked regression(>4mm), was in 19%, moderate regression(2~4mm) in 59% snd minimal regression(<2mm) in 22%. 4. The clinical results were correlated to amount of regression of herniated nucleus pulposus.