Abstract: Objective:To analysis of the causes of Lumbago-leg pain,and to explore the roles of imaging modalities for evaluation these diseases.Methods:The clinical and imaging data of one hundred and ninety-eight patients with Lumbago-leg pain were analyzed retrospectively.Results:The positive rate of Lumbago-leg pain is 89.4% by X-ray, CT-positive rate is 96.7%, and there are 144 cases suffered from lumbar intervertebral disc protrusion.Among of 25 cases of negative findings by X-ray and CT, 2 cases of intraspinal tumor, 3 cases of metastases tumor and 8 cases of ankylosing spondylitis were diagnosised by MRI.Conclusion:The causes of Lumbago-leg pain are very complex, and the most common cause is lumbar disc protrusion.X-ray can be used as an necessary technique, MRI should be used as the preferred method, especially in cases of tumor in vertebral canal,if the patients' conditions does not been permitted to MRI, CT can substitute for it, CT scan has higher diagnostic value to the lumbar disc protrusion.