Background and Study Aims: There is a paucity of literature on beginners' training and on its connection with patient safety for transforaminal epidural steroid injections (TFESIs). This study retrospectively assessed the learning curves and associated complications of neurosurgery residents never previously exposed to TFESI and compared them with experienced board-certified faculty neurosurgeons (BCFNs). Material and Methods Procedure time in minutes, dose-area product (DAP) in cGy*cm(2), periprocedural observations, and complications in 354 TFESIs for radicular pain secondary to lumbar disk herniation or lumbar spinal stenosis were extracted from operative notes and the electronic infiltration logbook in the per-injection format. Learning curves for 238 residents and 116 BCFN TFESIs in terms of procedure time and DAP were estimated using monotone regression. Results Residents' TFESI procedure time and DAP reached BCFN level (4.7 minutes and 140.2 Gy*cm(2)) after 67 and 68 cases, respectively. Residents' TFESIs were unsuccessful in 1.7%, mostly for severe obesity and hypertrophied facet joints, but no severe complications were noted. Obesity, however, did not result in increased procedure times or radiation exposure in general. Residents were faster and required less fluoroscopy in TFESI of the upper lumbar nerve roots than for L5 or S1 in particular. Conclusion The residents' learning curve for TFESIs in terms of procedure time and radiation exposure can be overcome safely after < 70 TFESIs. An outcome analysis correlating to the interventionalist's training level would be worth investigating in future studies.