Background: Owing to the anatomical difference between the far lateral herniation of the lumbar disc (FHLD) and the intraspinal herniation of lumbar disc (iHLD), the outcome of transforaminal epidural steroid injections (TFESI) in patients with FHLD seems to be different from that in patients with iHLD. However, few studies have evaluated the efficacy of TFESI in FHLD. Objective: To evaluate and compare the efficacy of TFESI in FHLD and iHLD patients. Study Design: A retrospective design. Methods: There were 15 and 70 patients in the FHLD and iHLD groups, respectively. Patients received a fluoroscopically guided TFESI. Failure rates of TFESI were recorded, and questionnaires, including a visual analog scale (VAS) for leg pain and Oswestry Disability Index (ODI) were administered before the initial injection, at 2 weeks, 6 weeks, and 12 weeks after the injections. Results: There was no failure for TFESI in the iHLD group, while 9 patients had to undergo alternative blocks in the FHLD group due to lancinating leg pain when the needle was advanced for TFESI. In the iHLD group, there was a statistically significant improvement in the VAS and ODI score 12 weeks after injection. Considering only successful cases of the FHLD group, significant improvement in the VAS and ODI score was also demonstrated in the FHLD group 12 weeks after injection. Moreover, there was no statistically significant difference of the VAS and ODI between the both groups. Limitations: A relatively small numbers of cases were included in the FHLD group. Conclusion: The current study suggests that an alternative needle placement technique for TFESI appears to be necessary for FHLD patients. Key words: Far lateral herniation of lumbar disc, intraspinal herniation of lumbar disc, transforaminal epidural steroid injection, safe triangle, herniated lumbar disc, visual analog pain scale, Oswestry disability index, radiculopathy