Background/aim: The aim of this cadaveric study was to investigate the erector spinae plane block (ESPB) in lumbar region and to elucidate the possible mechanisms of action of these injections in lumbar radicular pain by means of detecting expected dye dispersion to the neural structures. Materials and methods: Ultrasound-guided lumbar ESPB was performed in three formaldehyde-embalmed human cadavers. For this purpose, a 10 mL of methylene blue was injected into the fascial space between the L4 transverse process and the erector spinae muscles. Then, the cadavers were dissected, the cephalocaudal and lateral spread of the dye was examined, and the involvement of the dorsal rami, dorsal root ganglia and ventral rami were analyzed. The distribution into the epidural space was also evaluated. Results: The involvement of the dorsal rami was found to extend up to the T12 level and down to the L5 spinal nerves. Although dye dispersion was detected on the dorsal root ganglion in all specimens, it was found to be limited to one or two levels, unlike the dorsal rami. In half of the specimens, distribution to the ventral ramus and posterior epidural space was observed. Conclusion: The lumbar ESPB is an interfascial block technique, which can be used to avoid complications, taking advantage of ultrasound. It can be preferred as an alternative to periradicular injection in patients with lumbar radicular pain. It seems to be useful for regional anesthesia, particularly with an increased injectate volume.