Peppermint oil, extracted from Mentha piperita, has been show to reduce gastric spasms in vivo and to exert antiemetic properties. Although menthol, the main constituent of peppermint oil, could be responsible for these effects, up to now, studies on its action are lacking. The aims of the study were to analyze, in mouse stomach, the effects of menthol on the spontaneous mechanical activity, which was detected in vitro as changes of intraluminal pressure, and to clarify the mechanism responsible for the effects observed. Menthol (1 mM –3 M) produced a concentration-dependent relaxation, which reached about the 75% of the relaxation induced by isoproterenol (1 mM). The inhibitory effects of the menthol were antagonized by tetrodoxin, a blocker of neuronal voltage-dependent Na⁺ channels, or w-conotoxin GVIA, a blocker of N-type voltage-dependent Ca²⁺ channels. Nw-nitro-L-arginine methyl ester (L-NAME), a blocker of nitric oxide synthase, apamin, a blocker of small conductance Ca²⁺-dependent potassium channels or [Lys1,Pro2,5,Arg3,4,Tyr6]VIP^7–28, a vasoactive intestinal peptide receptor antagonist, failed to affect the gastric responses to the menthol. On the contrary, guanethidine, a blocker of noradrenaline release or atropine, a muscarinic cholinergic receptor blocker, significantly antagonized menthol effects. The present results suggest that menthol is able to induce gastric relaxation through adrenergic neurons, that, in turn, reduce acetylcholine release.