In order to investigate a pathogenesis of liver damage induced by skin burn, thermal injury was induced by scald burn on entirely dorsal surface in rats (total body surface area 30%) except for inhalated injury. At 5 and 24 h after scald bum, biochemical assay and morphological changes in skin tissue, serum and liver tissue were examined. The effects of bum injury on the levels of glutathione, lipid peroxide and on the activities of oxygen free radical generating and scavenging enzymes have been determined in association with observing of histologic and ultrastructural changes, measuring the protein concentration in plasma, and counting the number of intravascular polymorphonuclear leukocytes. The activity of xanthine oxidase, an enzyme of oxygen free radical generating system. was elevated (p<0.01) in serum, but not in skin and in liver tissue. Futhermore, thermal injury decreased not only the protein concentration in plasma but also the number of leukocytes, that indicates induction of edema formation with protein exudation and inflammation by neutrophil infiltration into the internal organs. These data suggest that acute dermal scald burn injury leads to liver damage, that is related to elevation of xanthine oxidase activity in serum. Xanthine oxidase may be a key role in the pathogenesis of liver damage induced by skin burn.