Background/Aims: Ischemia-reperfusion injury is responsible for organ damage in a variety of pathological events such as myocardial infarction, stroke and graft failure after organ transplan- tation. Reperfusion is essential for the salvage of ischemic state. But reperfusion itself is also thought to be accompanied by its own component of injury. Reperfusion is a particularly potent stimulus for free radical formation. Free radical attack on biological membranes, such as the plasma membrane, mitochondria and endoplasmic reticulum, can lead to the oxidative destruction of the polyunsaturated fatty acids of the membranes through lipid peroxidation. In the present study, the possible protective effect of alpha-tocopherol against 15 min ischemia and subsequent 60 min reperfusion in the rat liver was investigated. Methods: Ischemia of the left and median lobes was induced by ligation of the left portal vein and the hepatic artery for 1S min. 60 min after reperfusion, experiments were initiated. Results: In ischemia-reperfusion on liver, serum AST and ALT activities and the level of malondialdehyde(MDA) in the liver homogenate were significantly increased. In addition, levels of cytochrome P-450 decreased in a microsomal fraction during ischemia-reperfusion. When rats were pretreated with alpha-tocopherol(200 mg/kg p.o, daily for 3 days), alpha-tocopherol suppressed the elevation of serum AST, ALT and MDA level and the decrease in cytochrome P-450 content. Conclusions: Free radicals play a major role in ischemia- reperfusion injury in the liver. Alpha-tocopherol exerts its beneficial effect on liver ischemia-reperfusion injury. Therefore, anti-oxidative effect of alpha-tocopherol is considered a probable suppressing mechanism on liver injury caused by ischemia-reperfusion. (Korean J Gastroenterol 1995;27:323 - 330)