Background : We studied the effects of lumbar spinal root block (RB) prospectively in 21 patients who had suffered from low back pain with radiating pain even treated epidural steroid injection three times. Method : RB was performed under the fluoroscopic C-arm guide. When the needle was in correct position, we confirmed the needle placement and expected drug spreading by injection of contrast medium ($Isovist^{(R)}$-300, Sobering, Germany). Next 2% mepivacaine 1 ml mixed to 40 mg of Depomedrol was injected. Pain assessment was carried out 7 days after RB by numeric pain score regarding the pain just before RB was 10. Remained pain after RB was graded as excellent; 0-2, good; 3-5, bad; 6-8 and poor 9-10. Results : Mean age of the patients was 52.3 years. 38.1% and 47.6% of the patients showed excellent and goo dresults after RB, respectively. Conclusion : We concluded that RB is easy and safe procedure to perfirm and effective for the treatment of remnant pain following epidural steroid injection, especially in the patients who had spinal stenosis.