Gastrointestinal duplications are rare congenital malformations occurring in embryonic period of development of digestive system. These abnormalities are usually found in infancy or early childhood. Clinical presentation is extremely diverse depending on dimensions, localization and type of duplication. The authors present duplication of antral and pyloric parts of the stomach, the 1st segment of the duodenum and pancreatic tail. Mother with a 6-month-old child turned to the hospital. According to the mother, the child was sick for about 3 days when episodes of periodic anxiety first appeared. Upon admission, abdominal neoplasm was suspected after ultrasound. On the second day after admission, anxiety increased. There was impairment of appetite, and the child rejected food. Abdominal asymmetry in umbilical area was observed. Considering clinical data on intestinal obstruction, emergency transverse right-sided laparotomy was performed. A tubular structure was found resembling intestinal tube was found between the stomach and transverse colon. Surgeon found duplication of antral and pyloric parts of the stomach, the 1st segment of the duodenum and its perforation. During further revision, additional pancreatic tail was diagnosed. En-bloc resection of gastrointestinal duplications was carried out. Postoperative period was uneventful. Enteral feeding was initiated after 5 days, and the patient was transferred to surgical unit. The child was discharged after 12 postoperative days.