The herniated nucleus pulposus(HNP) is a very common disorder. In those patient, who do not respond, moredirect therapeutic measures, may be necessary. The chymopapain cheomonuclelysis, after two decades of development,has provided a variable alternative to surgical diskectomy for treatment of HNP. The changes of CT scan follow-up 1 month and 3 month that occur in the disks of those patient who respond to chymopapain chemonucleolysis must bedefined and evaluation of temporal radiographic changes may also help clarity mechanism by which chemonucleolysisrelieves sciatic pain caused by HNP. The results were as follows: 1. Our data indicates that chymopapainchemonucleolysis was effective in 70% and 90% of patients at both 1M. and 3M. follow-up.(average 80%) 2. At 1M.follow-up, a successful response was noted in 70% of patients, with all significant intervertebral disc spacenarrowing(average 2.7mm) and 30% of them showing an observable diminution in the herniated disc fragment(average 0.8mm). At 3M. follow-up, a successful response was noted in 90% of patients, with 70% of them showing significant narrowing (average 1.2mm) and observable diminution in the herniated disc fragment(average 1.5mm). The refor, with3M. follow-up, the CT changes did become more pronounced with greater number of patients exhibiting a diminution of the disk herniation and interspace narrowing, and associated with more progressive improvement of clinicaloutcome. 3. New vacuum phenomenon and extradiskal effects of chymopapain appear to be absent. 4. At 1M. follow-up, Housefield Unit(HU) of disk is generally increased(average 8.8HU) and at 3M. follow-up, it is decreased(average6HU).