Phospholipase A 2 (PLA 2) from the venom of the snake Trimeresurus flavoviridis produced an increase in resting tension of isolated strips of rat stomach fundus. The contraction of the fundus strips induced by the PLA 2 were significantly inhibited by treatment with 10 −6 M indomethacin and in Ca 2+-free medium, while treatment of the fundus strips with nordihydroguaiaretic acid caused a marked potentiation of the PLA 2-induced contraction. Atropine (10 −6 M), chlorpheniramine (10 −6 M) and methysergide (10 −6 M) had no effects on the contractions induced by PLA 2, while tetrodotoxin (10 −6 M) significantly potentiated the contraction. From these results, it appears that exogenously applied PLA 2 may cause contraction of the rat stomach fundus through the liberation of endogenous arachidonic acid which may then be transformed into prostaglandins.