Purpose Lumbar disc herniation is the most common spinal disorder and various less invasive techniques such as microdiscectomy have been described. However, postoperative pain management in patients undergoing discectomy is still commonly inadequate. Erector spinae plane (ESP) block is a relatively easier technique with lower risks of complications, and can be performed to provide postoperative analgesia for various procedures. The current study aimed to determine the effect of ESP block on postoperative analgesia in patients who underwent elective lumbar disc herniation repair surgeries. Methods Fifty-four ASA I-II patients aged 18-65 years scheduled for elective discectomy surgery were included in the study. Patients were randomized either to the ESP or control group. Ultrasound-guided ESP block with 20 mL of 0.25% bupivacaine was performed preoperatively in the ESP group patients and a sham block was performed with 20 mL normal saline in the control group patients. All the patients were provided with intravenous patient-controlled analgesia devices containing morphine. Morphine consumption and numeric rating scale (NRS) scores for pain were recorded 1, 6, 12, and 24 h after surgery. Results A significantly lower morphine consumption was observed at 6, 12, and 24 h timepoints in the ESP group (p < 0.05 for each timepoint). Total morphine consumption at 24 h after surgery decreased by 57% compared to that of the control group (11.3 +/- 9.5 mg in the ESP group and 27 +/- 16.7 mg in the control group). NRS scores were similar between the two groups. Conclusion This study showed that ESP block provided effective analgesia in patients who underwent lumbar disc herniation surgery.