To study morpho-functional peculiarities of chronic gastroduodenal pathology in smoking children. <...> Patients and methods. 136 children with chronic gastroduodenal pathology participated in the investigation. <...> All children underwent esophagogastroduodenoscopy with pH-metry and morphologic examination of biopsy specimens of antral stomach’s and duodenum’s mucosa. <...> To evaluate mucosal barrier protection coloration of biopsy materials for neutral and acid mucopolysaccharides was carried out. <...> Immunohistochemical investigation of biopsy materials for detection of prostaglandin E expression level was performed besides. <...> Main morpho-functional peculiarities of infl ammation and cytoprotective function of gastroduodenal organs’ mucosa in children dependently on smoking status are represented in the article. <...> According to the received data, chronic gastroduodenal pathology in active smokers was characterized by prevailing of high degree of gastric and duodenal mucosa infl ammation on the background of microcirculatory disorders and decreasing of neutral mucopolysaccharides level and PgE expression in gastric mucosa. <...> Согласно полученным данным, у большинства курящих пациентов хроническая гастродуоденальная патология протекала с преобладанием среднетяжелой и тяжелой степени воспаления слизистой оболочки желудка и двенадцатиперсной кишки на фоне микроциркуляторных нарушений и снижения продукции нейтральных мукополисахаридов и экспрессии простагландина Е. <...> Eastern Europe» 2016, volume 4, № 4 Оригинальные исследования Prevalence of gastric and intestinal diseases makes 148.95‰ among children’s population in Ukraine. <...> Chronic gastritis and gastroduodenitis are the most widespread forms of chronic gastroduodenal pathology (CGDP) and make 31.09% out of the whole gastric and duodenal pathology [2, 3, 5]. <...> Chronic gastroduodenitis (CGD) is a chronic recidivating phasic infl ammation of stomach’s mucosa (SM) and submucosa and duodenum’s mucosa accompanying by cellular infi ltration, physiological regeneration disorders with a tendency to progressing and gradual development of mucosal atrophy, stomach’s and duodenum’s secretory, motor and, sometimes, incretory functions failure [1, 4]. <...> Gastritis and gastroduodenitis are clinical-and-morphological diagnoses, which may be particularly verifi ed by instrumental and histological examinations [6, 8]. <...> It is well known that complicated heredity, quantitatively and qualitatively improper feeding, H. pylori contamination, ulcerogenic infl <...>