The stereological and histopathological evaluation of the effect of Thymoquinone on peridural fibrosis following laminectomy in rats Abstract Background/aim: This study was aimed to investigate the effects of thymoquinone, which is the essential bioactive component of the volatile oil of Nigella sativa on the peridural fibrosis in rats following laminectomy. Materials and methods: Twenty female Wistar Albino rats were used in our study. The rats were randomly divided into two groups as Sham and Surgery+Thymoquinone. Both groups underwent laminectomy at L1, under general anesthesia. The sham group was not subjected to any drug application. The second group was treated with intraperitoneal 10 mg/kg thymoquinone per day for a period of 28 days, following the same surgical procedure. All the groups were sacrificed after four weeks and the laminectomy area was examined in terms of new bone volume, capillary volume and fibrosis volume using stereological approaches. Results: Statistically significant differences were found between the Sham and Surgery+Thymoquinone groups, in terms of the new bone volume (p=0.01), capillary volume (p=0.01) and fibrosis volume (p<0.001). It was noted that thymoquinone caused significant increase in the new bone volume and vascular volume and a significant decrease in the fibrosis volume. Conclusion: The results of our study indicate that thymoquinone is effective in decreasing the peridural fibrosis when applied on laminectomy model.