The dopamine agonist bromocriptine and L-dopa significantly inhibited whereas dopamine antagonist haloperidol aggravated the gastric lesions induced by pylorus ligation in mice as found earlier for rats. Furthermore, the successful use of a dopamine antagonist alone for the induction of gastric lesions also in mice was demonstrated, since the gastric lesions were induced by a single dose of haloperidol without any additional noxious treatment. Bromocriptine successfully inhibited both the gastric lesion-potentiating as well as the gastric lesion-inducing effect of haloperidol.