Abstract: Objective To study the effect of dexmedetomidine (DEX) pretreatment on antioxidant ability of kidney and liver in rats following renal ischemia/reperfusion (I/R) injury. Methods Ninety male SD rats were randomly divided into DEX pretreatment group, I/R injury group, and sham operation group (30 in each group). DEX (100 μg/kg) was injected into the abdominal cavity of rats in DEX pretreatment group 30 min before the model was established. A renal I/R injury model was established for I/R injury group and sham operation group, respectively, by injecting 0.9% sodium chloride (100 μg/kg). Serum levels of superoxide dismutase (SOD), nitric oxide (NO) and lactate dehydrogenases (LD), reduced glutathione (GSH) and total antioxidant capacity (T- AOC) in liver and renal tissues were measured 2, 8 and 24 h, respectively, after reperfusion. Results The serum SOD level and T-AOC were higher and the serum NO level was lower in DEX pretreatment group than in I/R injury group (P< 0.05). The serum LA level was signifcantly lower while the serum SOD and NO level and T-AOC were signifcantly higher in DEX pretreatment group than in I/R injury group 8 h after reperfusion (P< 0.05) and the serum LA level was signifcantly lower in DEX pretreatment group than in I/R injury group 8 and 24 h after reperfusion (P< 0.05). Conclusion DEX pretreatment can increase the antioxidant ability of kidney and liver in rats following renal I/R injury, thus reducing LA accumulation.