Purpose: Lumbar disk hernia is very common reason for spinal surgery and usually treats with surgical interventions. The primary aim of this randomized controlled study was to determine the effect of low thoracic ultrasound guided erector spinae plane (ESP) block on postoperative pain management in lumbar microdiscectomy surgery. Materials and Methods: Totally 42 adults scheduled for elective lumbar microdiscectomy surgery and assigned into two groups as Group ESP and Group Control. Anesthesia was induced with propofol 2mg/kg, rocuronium 0.6 mg/kg, fentanil 2µg/kg and maintained with total intravenous anesthesia (propofol 4-8 mg/kg/h and remifentanil 0.03-0.05 µg/kg/min), N2O/O2 mixture %60/40 for all patients. When patients were positioned at prone, ESP or sham block performed bilaterally. ESP performed with bupivacain 0.5% 15 mL+lidocain 2% 5 mL in ESP group and saline 20 mL for sham group at the T10 level of spine. The postoperative analgesia provided with morphine 0.1 mg/kg intravenously and diclofenac Na 75 mg intramuscularly at last 30 minutes of surgery for all patients. Postoperative visual analog scale (VAS) scores, meperidine requirements and patients’ satisfaction were recorded. Results: There were significant differences between Group ESP and Group Control in meperidine requirement, VAS scores at rest and leg movement and patients’ satisfaction. Time to first analgesic need was median 62.5 min (interquartile range 5-180) in Group ESP and median 7.50 min (interquartile range 5-10) in Group Control. Conclusion: ESP can significantly reduce postoperative pain scores (VAS at rest and leg movement), meperidine requirement and can provide better patients’ satisfaction, postoperatively.