The antisecretory effects of esaprazole on basal gastric secretion and on pentagastrin-stimulated secretion (6 micrograms/kg subcutaneously) were evaluated in two trials carried out on 19 healthy volunteers. All trials were carried out according to a randomized double-blind crossover design versus a placebo. The oral administration of 900 mg of esaprazole 30 min before starting the secretion test, induced a certain reduction of all the gastric secretion parameters. The reduction of both basal and stimulated secretion was significantly (p less than 0.001) more evident after the oral administration (gastric instillation) of 1800 mg of the drug 60 min before starting the study. Esaprazole was shown to have a dose-dependent antisecretory activity which was particularly evident on secretion volume and acid output.