Background. Viral hepatitis C (HCV) is not only as a liver disease but also as a systemic (generalized) infection that affects other organs, in particular, the pancreas and gastroduodenal zone. The state of the gastrointestinal mucosa in combined course of chronic pancreatitis (CP) and chronic HCV is little studied, but extremely relevant, as it is important for the clinical course, the quality of life of patients, as well as for assessing the safety of the performed (etiotropic, etc.) and planned restorative comprehensive treatment of such patients. The purpose is to evaluate the morphological changes of the gastroduodenal mucosa of patients with chronic pancreatitis associated with chronic viral hepatitis C who were treated etiotropically. Materials and methods. Thirty patients with CP and 65 patients with CP in comorbidity with chronic HCV after etiotropic treatment of HCV were examined. Regardless of the HCV genotype, they received a course of treatment with sofosbuvir at a dose of 400 mg and velpatasvir 100 mg in the morning after meals for 3 months (some patients took daclatasvir at a dose of 60 mg also in the morning after meals for 3 months instead of velpatasvir). The period after diagnosed and treated HCV before the examination was on average (2.35 ± 0.61) years. All patients underwent a morphological study of gastric and duodenal biopsy samples obtained by esophagogastroscopy. The prepared samples were evaluated according to the international OLGA and OLGIM systems based on the evaluation of 5 gastric biopsies (1 from the corner of the stomach, 2 from the body, and 2 from the antrum) with a description of the main pathomorphological changes evaluated on a visual analog scale. Alcian yellow and toluidine blue were used to detect H.pylori. An own system for assessing the morphological state of the gastroduodenal mucosa was also proposed. Results. The detected structural changes indicate the presence of chronic atrophic gastritis with moderate dysplasia of the glandular epithelium. Stage of chronic gastritis according to the OLGA system was III. Stage of chronic gastritis according to the OLGIM system was III. Thus, the practically asymptomatic course of quite significant gastroduodenal changes in CP combined with chronic HCV requires additional therapeutic influence, as well as an assessment of comprehensive treatment based on the effect on the gastroduodenal mucosa. In case of changes in gastroduodenal mucosa in CP on the background of chronic HCV, in contrast to those with isolated CP, a significantly higher level of inflammatory infiltrate density (moderate (2+) vs. mild (1+)) is determined, which is accompanied by moderate neutrophilic infiltration (2+) vs. mild (1+) and mild lymphohistiocytic infiltration (1+) versus no such infiltration (0), the appearance of intestinal metaplasia (2+) and moderate non-metaplastic glandular atrophy (2+) versus the absence of metaplasia (0) and mild non-metaplastic glandular atrophy (1+), as well as zones of metaplastic atrophy (1+), which was manifested by the appearance of Paneth cells and goblet cells. In CP with chronic HCV, mucosa has atrophic changes. Metaplasia is manifested by a change in cellular phenotype: complete intestinal metaplasia type I–II is manifested by the appearance of Paneth cells and goblet cells; incomplete — by the presence of columnar epithelium and goblet cells; colonic metaplasia — by enlargement of the glands and the absence of Paneth cells. Conclusions. It was proved that the state of the gastric and duodenal mucosa in the group of patients with CP and chronic HCV was significantly severe than that in isolated CP: lymphohistiocytic infiltration of the mucous membrane was detected 2.68 times more often, non-metaplastic infiltration glandular atrophy (there was practically no glandular atrophy in the group of isolated CP) — 12.65 times more often, metaplastic atrophy (it was not detected in the group of CP) — 10.64 times more often, acute leukocyte infiltration — 2.31 times more often, dysplasia of the mucosal epithelium (with isolated CP, mild dysplasia was detected) — 7.30 times more often, erosion of the mucosal epithelium — 3.07 times more often, focal hyperplasia of the glands — 3.88 times more often, intestinal metaplasia — 12.89 times more often, which was practically absent in CP. In general, the total number of pathological signs of the mucous membrane in the group of CP with comorbid chronic HCV was found to be 2.76 times higher than that in isolated CP.