In order to understand the mechanisms of superoxide dismutase (SOD) against inflammatory lesion in hamster cheek pouch, glutathione peroxidase (GPx) activity in the cheek pouch mucosa was assayed in different time. The efficacy of GPx scavenging lipid peroxide was also measured. In the SOD group GPx activity decreased significantly in the early stage (8 h). But the level of lipid peroxide in the SOD group not increase at the same time. The results of the model group were contrary. It was implied that exigenous SOD scavenged lipid peroxide in the oral mucosa sufficiently in stead of GPx.