Effects of n-butanol extract of Atractylodes japonica Koidz. ex Kitam. (NEG)on gastric ulcer were stud ied in 6 experimental models. The results showed that NEG inhibited the formation of gastric ulcers induced by acetic acid,plylorus-ligation or indomethacine,but it lacks efficacy in gastric ulcers induced by stress or re serpin. NEG at a dose of 0. 18g/kg significantly increased the PGE2 content in gastric juice (P