Ethanol induces compoundhemorrhagic gastric lesions and causes a dose-dependent decrease in the concentration of endogenous nonprotein sulfhydryls in rat gastric mucosa. Sulfhydryl-containing drugs protect rats from ethanol - induced gastric lesions. Based on this findings, we investigated the involvement of sulfhydryl compounds in the antioxidant effects of Puerariae radix, a traditional herbal medicine, against ethanol - induced gastric lesions in the absence and presence of iodoacetamide(IDA. sulfhydryl blocking agent) in rats. respectively. Because of the known role of sulfhydryls in gastric cytoprotection, its role in gastric antioxidation was of intrest. In vitro, Puerariae radix extract(PRE) reduced linoleic acid autooxidation and exert DPPH radical scavenging effect. In vivo. PRE increased antioxidants(SOD, catalase. GSH) and reduced lipid peroxide level in ethanol-induced gastric mucosal lesions. But treatment with PRE plus IDA significantly inhibit the antioxidant effects such as SOD and GSH but did not affect catalase levels. These results suggest that Puerariae radix may play roles in the gastric cytoprotection through antioxidant effects and increase of SOD activity and GSH level are dependent of endogenous sulfhydryls.