Objectives: Epidural fibrosis (EF) is a part of the normal physiological tissue response to laminectomy and it is an important cause of failed back surgery syndrome (FBSS). Osteoprotegerin (OPG) is a soluble member of the tumor necrosis factor receptor family, and is expressed in high concentrations by a variety of tissues and cell types. The objective of this study was to evaluate the relationship between serum OPG levels, and the existence of postoperative EF in patients with lumbar disc herniation. It has been suggested that cytokines and growth factors, which play a role in the wound healing, may enhance the expression of OPG. Methods: Forty women who underwent surgery for lumbar disc herniation were included in this study. Postoperative MRI was performed to assess EF in all patients.