We evaluated the effect of simvastatin (SV) on the oxido-redox state in rat livers submitted to ischemia-reperfusion (I/R). Rats received SV (groups: S, S-IR) or saline solution (groups: C, C-IR) intragastrically (25 mg/kg) for 21 days. Before homogenization, rat livers (C-IR, S-IR) underwent ischemia (40 min) and reperfusion (60 min). Activities of such antioxidative enzymes as superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) as well as lipid peroxides (LPO) level as indicator of oxidative stress were then estimated in the homogenates. All these parameters were measured spectrophotometrically. Additionally, alanine and asparagine aminotransferase (ALT, AST) levels were estimated in the blood before and after I/R. In groups C and S all examined parameters were similar regardless of SV-treatment. I/R produced significant increases in GPx and CAT activities only in the C-IR group. Conversely, GPx activity was significantly decreased and ALT and AST increased significantly in the S-IR group. SV did not evoke any noticeable protective changes in rat livers after 3 weeks of treatment. After I/R, some of the observed properties could suggest that SV may have even made liver function and the oxidative state worse.