Aims: This study aims to investigate the effectiveness of transforaminal epidural steroid injection (TFESI) in patients with lumbar radicular pain or radiculopathy caused by different spinal pathologies. Methods: One hundred and seventy seven patients who underwent single transforaminal epidural steroid injection were included in the study group and divided into 3 subgroups (central spinal stenosis + lateral recess stenosis, foraminal stenosis, lumbar disc herniation) according to existing spinal pathology. Patients' visuel analogue scale (VAS) measures and Oswestry Disability Index (ODI) scores were recorded and the patients who give favourable response to treatment were called respondents and who were not called as non-respondents. Subgroups were compared statistically at the end of 12 months. Results: Sixty patients (33.9%) were considered as respondents and 117 patients (66.1%) were non-respondents in the entire study group. Patients with foraminal stenosis included the vast majority of the respondents and showed better results of pain relief as opposed to patients of other groups at the end of 12 months (P < 0.001). Conclusion: TFESI was an effective treatment modality for pain relief and functional improvement in patients with foraminal stenosis. However, it could not produce the same results in patients with central spinal stenosis and lumbar disc herniations.