Introduction: Some stressful stimuli are capable of inducing resistance when applied before ischemic events, which are known as preconditioning. The preconditioning by hypothermic perfusion has been validated in the heart perfused at 26 °C (Khaliulin et al. 2007). We have previously shown that perfusion of the liver at 22 °C improves antioxidant/oxidant profile compared with perfusion at 26 °C. Therefore, this study was designed to demonstrate the preconditioning effect of perfusion at 22 °C applied prior to an episode of ischemia in isolated rat liver focusing on oxidative stress indicators. Material and Methods: Fifteen male rats (200-250g) were anesthetized (sodium pentobarbital 60 mg.g-1 I.P.) and then underwent laparotomy. The livers were perfused with oxygenated Krebs Henseleit buffer (95% O2/5% CO2, pH 7.4 at 37 °C) (Vairetti et al. 2006), excised and placed in an isolated perfused rat liver system at a flow rate of 4 mL.min-1.g-1. Livers were randomly divided into three experimental groups. The buffer temperature varied as follows: 20 min of normothermic perfusion in Ischemia/reperfusion (IR) group and 10 min of hypothermic perfusion (22 °C) + 10 min of rewarming (37 °C) in preconditioning + ischemia/reperfusion (PC + IR) group. Both groups underwent 40 min of ischemia and 20 min of reperfusion. Sham livers (S) were frozen without treatment. The levels of lipoperoxidation products (TBARS, 4-HNE and MDA), nitric oxide derivates, and protein oxidation indicators (AOPP) were measured in tissue homogenates. Paraffin-embedded liver sections were evaluated after incubation with antibodies anti-4-HNE. Results and Discussion: All data were expressed as percentage of Sham values ± S.E.M analysed by two-way ANOVA.TBARS increased after ischemia/reperfusión (IR) treatment but this harmful effect was reverted by preconditioning(from 207.2 ± 22.5 in IR to 95.6 ± 12.6 in PC+IR, p<0.01). The protection was also evident in MDA production (decreasing from 147.5 ± 16.9 to 83.1 ± 8.5, p<0.01) while was less clear in 4-HNE (from 182.2 ± 7.6 to 140.9 ± 6.0). The PC treatment also tended to diminish the liver content of nitric oxide products (from 216.3 ± 36.6 to 78.5 ± 48.21) and AOPP (from 108.8 ±8.4 to 72.4 ± 10.3). Histological examination of liver sections showed an increase in sinusoidal spaces in IR group that is less evident in the PC + IR group while immunohistochemistry assays showed a cytosolic location of 4-HNE antibodies in IR group. Conclusion A 10-min hypothermic perfusion was capable of reducing oxidative damage in the liver when applied just prior to an ischemic episode that shows its value as a preconditioning stimulus. The tissue damage markers seem to indicate a modulation of the MDA production as main effect of this treatment.