Aim. To comprehensively study the course of gastric ulcer disease (GUD) and duodenal ulcer disease (DUD) concurrent with chronic duodenal insufficiency (CDI). Materials and methods. Ulcer disease (UD) was verified on the basis of the results of clinical and fibrogastroduodenoscopic examinations. The data of contrast duodenography and cavitary manometry were used to identify CDI. Gastroduodenal motor activity was investigated using the peripheral electrogastrograph EGG-4M. The results of pH measurements were employed to assess the state of gastric acid secretion and duodenal pH values. Results. A comprehensive examination was made in 106 patients with UD concurrent with CDI (a study group) and 30 UD patients without CDI (a comparison group). Epigastric pain was noted in the patients with GUD in the study and comparison groups (91.5 and 84.6%, respectively), but the pain was mainly aching in the patients with concomitant CDI and more intense (77.8%) in those without this condition. In the study group, heartburn was more common in patients with GUD and DUD (75.3 and 71.4%, respectively) than in those with UD in the comparison group (28.5 and 37.5%, respectively). Helicobacter pylori tests were positive in 23.8% of the patients in the study group and in 57.2% in the comparison group. Electrogastrography indicated that the patients with GUD and CDI had bradygastria and hypokinesis on an empty stomach; the electrical activity was reduced after eating. In the comparison group, tachygastria and hyperkinesis were detected on an empty stomach; these postprandial indicators were elevated. H. pylori tests were positive in 34.7% of the patients with DUD and CDI and in 63.6% of those with DUD without CDI. The postprandial electrical activity increased in patients with DUD and decreased in the comparison group. The specific features of changes in gastric and duodenal pH values in GUD and DUD concurrent with CDI in comparison with the isolated course of UD. Conclusion. The immediate and long-term follow-ups show that GUD and DUD concurrent with CDI run a more persistent course; the time of ulcer healing increases and the periods of remission decrease.