Liver failure is still a significant clinical problem after transplantation surgery, tissue resections (Pringle maneuver), and hemorrhagic shock . The restoration of blood flow to an ischemic region leads to tissue injury at a greater rate than the original ischemic insult, an event called reperfusion injury. Despite advances in surgical techniques, I/R injury remains a significant clinical problem. In this research, we studied effect of simvastatin pretreatment on liver and lung injury induced by hepatic ischemia/reperfusion. Rats were subjected to 30 min of ischemia followed by 24 hr of reperfusion. Simvastatin (10 mg/kg) administered orally since 3 days before operation. After reperfusion time, serum ALT,AST,LDH and TNF α level were studied and liver and lung tissue were stained with hematoxylin and eosin and TUNEL for detecting apoptotic cells. The serum aminotransferase activity,LDH and TNF α level were increased markedly by hepatic I/R, which were suppressed significantly by simvastatin. Tissue injury index and number of apoptotic cells via TUNEL staining in liver and lung were higher in I/R group comparing to I/R+simvastatin group. These results suggest that melatonin ameliorates I/R-induced liver and lung tissue damage by inhibiting the level of inflammatory and the apoptotic pathways. Therefore, simvastatin administration may provide protection against the adverse effects of I/R injury in liver transplantation.