This study was carried out to investigate the protective effects of GaMiHyangSaYukGunJaTang on gastric mucosal lesions caused by indomethacin in rats.The test group was injected with indomethacin after the oral administration of GaMiHyangSaYukGunJaTang, while the control group was injected only with indomethacin. The lipid peroxidation level increased considerably in the control group, but superoxide disnurtase(SOD), catalase and glutathione(GSH) levels remarkably decreased. The following effects induced by indomethacin were observed in the stomach of the control group; mucosa hemoIThagic infarct, mucosa cell necrosis, leukocyte appearance, mucosa hemorrhagic erosion and gastric pit disawearance. In the test group, lipid peroxides level was significantly reduced compared with the control group While SOD, catalase and GSH levels considerably increased. The following effects were also observed in the stomach of the test group; mucosa hemorrhagic infarct, mucosa cell necrosis, leukocyte appearance and mucosa hemorrhagic erosion occured far less and gastric pit disappearance was not observed at all. This results suggest that GaMiHyangSaYukGunJaTang is effective in the remedy of gastric mucosal lesions as GaMiHyangSaYukGunJaTang suppresses the production of the lipid peroxides and free radicals induced by indomethacin and activates SOD, catalase and GSH.