OBJECTIVE: To investigate the protective effects of carvacrol on an experimental testicular torsion-detorsion rat model. STUDY DESIGN: Wistar male rats (n=48) weighing 230–250 g were assigned to 4 groups (8 per group): control, torsion, torsion-detorsion, and torsion-detorsion+ carvacrol–treated groups. Control group animals did not undergo any surgical operation. For the torsion group, the scrotum was opened (under general anesthesia) and the left testis twisted 720° clockwise and in the last 30 minutes of 3-hour ischemia; i.p. saline was injected. In the torsion-detorsion group, after ischemia the left testis was reperfused for 2 hours. The torsion/ detorsion+carvacrol group protocol was similar to that of the torsion-detorsion group but in the last 30 minutes of 3-hour ischemia, i.p. 20 mg/kg carvacrol was administered. RESULTS: Malondialdehyde (MDA) was highest in the torsion-detorsion group (p<0.01). The lowest catalase (CAT) value was found in the torsion-detorsion group. Decrease in glutathione (GSH) levels of the torsion and torsion-detorsion groups as compared to those of control and carvacrol groups was significant (p<0.01). The highest superoxide dismutase (SOD) value was in the control and carvacrol groups. Increased apoptosis and degeneration of spermatogenic cells with hyperplasic nuclei were mainly observed in the torsion and torsion-detorsion groups. The torsion-detorsion+ carvacrol group mostly showed regular histology, but Leydig cells were degenerated. ET-1 expression was increased in endothelial cells in the torsion and detorsion groups but negative in the carvacrol group. Bax expression was positive in luminal spermatogenic cells in the torsion group but negative in interstitial cells in both torsion and torsion-detorsion groups. In the carvacrol-treated group some luminal spermatogenic cells in seminiferous tubules showed positive Bax expression but weak in basal membrane cells and Leydig cells. CONCLUSION: Carvacrol influences spermatogenic cells with strong mitotic activity in basal membranes of seminiferous tubules and may prevent apoptotic development and signaling of these cells. © Science Printers and Publishers, Inc.