Objective CT-guided collagenase injection through posterolateral path into the interior and superficial prominence of the herniated lumbar disc in the treatment of L4-5 lumbar disk herniation.Methods The approach of posterolateral path to the prominence through intervertebral foramen and epidural space of L4-5 was established according to the analysis of anatomical features and vertebral medical images. The accuracy and safety of the approach were evaluated by CT scanning after epidural injection with air. CT-guided injection was operated in 66 cases of prolapse of L4-5 intervertebral disc confirmed by CT. Results Technical success was 100%. Followed up for 3 months to 3 years, 62 cases (93%) were markedly suecessfud with the effective rate of 93%. Twenty-three had CT re-examination three months later showed the prominences becoming smaller or disappeared in 22 patients having a resolved rate of 95%.Conclusions CT-guided injection of collagenase is one of the effective methods for the treatment of prolapse of L4-5 intervertebral disc.