Objective: To investigate the influential factors and clinical therapeutic effect of epidural injection of collagenase for the treatment of cervical intervertebral disc protrusion.Methods: 3700 Patients with cervical intervertebral disc protrusion determined by CT or MRI were involved in this study.They all received epidural injection of collagenase under fluorscopic guidance.Results: For all patients involved,the long-term excellent and good rate was 93.61~91.89%.No serious complications were observed.Conclusion: Epidural injection of collagenase has good therapeutic effect for the patients with cervical intervertebral disc protrusion.These effects depended on the adequate selection of potential candidates.