Acidity status of stomach in duodenal malrotation combined with duodenostasis The problem of gastro-duodenal ulcer diagnosis remain actual in developed countries having an incidence of 2 to 10% of the population (M.I Cuzin, 1990; Casumian S., 1997). Contemporary pharmacotherapy noted impressive success in treating these patients, but in 3% of cases of ulcer disease modern treatment with H2-blockers and proton pump inhibitors is ineffective. In a series of patients with ulcer disease, intraoperatively duodenum was marked with increased diameter, shape and atypical localization. Study of gastric secretion is a method that will support the surgeon for proper appreciation of stomach acidity, duodeno-gastric reflux, and for correct selection and individual pharmacotherapy, timely surgical intervention and monitoring efficacy of treatment applied. The main purpose of this study was assessment of diurnal change of pH level in the gastric body, antrum and cardia for the first time using the "Gastroscan – ГЭМ”.