Objective: To assess the preventive role of metformin on rat ovarian ischemia reperfusion injury. Materials and methods: Forty rats were divided equally into five groups; Group 1: sham, Group 2: surgical control with 3-hr torsion and detorsion, Group 3: 50 mg/kg p.o. metformin 30 min before 3-hr torsion, Group 4; metformin just after detorsion, Group 5; metformin 30 min before torsion and just after detorsion. Bilateral ovaries and blood sample were obtained seven days after detorsion for biochemical and histopathological evaluation. Results: Ovarian tissue total anti-oxidant status (TAS) levels were significantly increased in group 4 when compared to group 1, 2 and 3 (all p < 0.01). In addition, there was a significant decrease in tissue oxidative stress index (OSI) level in group 4 with respect to group 2 (p < 0.01). Moreover, serum levels of OSI were significantly higher in group 2 with respect to group 1 and 5 (both p < 0.05). Similarly, there was significant increase in serum levels of peroxynitrite in group 2 as compared to serum levels in group 3 and 5 (p < 0.01 and 0.05, respectively). Furthermore, there were significant decrease in histopathological scores metformin and sham groups when compared to rats in the control group (Group 2). Conclusion: Metformin reduces ischemia reperfusion injury in rat torsion detorsion model by improving histopathological and biochemical findings including TAS, OSI and peroxynitrite.