INTRODUCTION giving rise to ROS. 7, 8 Activation of lipid peroxidation is also one of the manifestations of the action of ethanol. 9–11 It has been shown that the metabolism of The reactive oxygen species (ROS) generation in biological tissues is dependent on oxygen consumption. ethanol forms-hydroxyethyl radical in the mouse liver microsomes12 and the generation of this free Exercise seems to generate ROS due to increased oxygen consumption. 1, 2 The increased production of radical in hepatic tissue has also been confirmed by comparative studies with spin-trapping agents. 13 ROS during exercise can cause oxidative tissue damage if these species are not scavenged by the antioxidant Cytochrome P-450 II E1 (an isozyme of cytochrome P-450) has been shown to serve as a catalyst in the system. The antioxidant system is comprised of antioxidant enzymes—superoxide dismutase (SOD), catalase production of ROS due to ethanol metabolism. 14, 15 Thus, free radical generation after a chronic adminis-(CAT) and glutathione peroxidase (GSH-Px)—and antioxidant substances (vitamins A, C, E and reduced tration of ethanol is likely to influence the hepatic antioxidant system and lipid peroxidation. Endogenous glutathione). Our laboratory has shown an increased antioxidant enzyme (AOE) activity in red blood cells glutathione (GSH) also plays an important role in scavenging ROS and in detoxification of drugs and after acute exercise in rats. 3 A recent review showed that physical exercise enhanced antioxidant enzyme chemicals in the liver. 16 While scavenging free radicals, GSH is oxidized to GSSG, which is reduced back to activity and altered the reduced glutathione (GSH) level in different tissues of animals. 4 GSH by glutathione reductase (GR). The GSH/GSSG ratio is a useful tool for determining oxidative stress Ethanol has been used by amateurs and athletes, 5 and marathon runners have also used alcoholic beverages as in tissues. 17 The depletion of hepatic GSH is a prime factor for initiation of lipid peroxidation during oxidaa carbohydrate and electrolyte replacement fluid. 6 Ethanol is extensively metabolized into cytotoxic acetalde- tive stress. 18 Both exercise as well as ethanol ingestion are known to exert oxidative stress to vital organs and hyde by alcohol dehydrogenase in the liver and acettissues of the body. 1, 2, 9, 19 However, the interactive effects of the combination of both on the hepatic antioxidant system have not been known. This study