Résumé : Sera from 36 patients with gastritis only and 26 patients with peptic ulcer were tested for the presence of neutralising antibodies against H. pylori vacuolating toxin. The frequency with which sera did neutralise the vacuolating toxin was not significantly different among the groups of patients with gastroduodenal ulcer infected either with toxigenic or nontoxigenic H. pylori strains (9/14 vs 4/12; ns) or in patients with gastritis only harbouring toxigenic H. pylori strains (8/12). By contrast, none of 24 sera obtained from patients with gastritis and harbouring non-toxigenic H. pylori strains did neutralise the vacuolating toxin. It is suggested that H. pylori vacuolating toxin is involved in the pathogenesis of peptic ulcer disease. © 1993, Gustav Fischer Verlag, Stuttgart · Jena · New York. All rights reserved.