Purpose: informing the doctors who provide aid to children of the peculiarity of the pathology. Methods: a 10-month-old boy who developed recurrent vomiting, cough, nasal discharge and fatigue was admitted to the hospital in his place of residence and diagnosed ARVI with abdominal pain syndrome. In spite of the treatment, the patient’s condition worsened, cerebral edema aggravated, and he received artificial pulmonary ventilation with a diagnosis of acute meningoencephalitis of unclear etiology, cerebral edema, and stage 3 coma. The patient was transferred to the republican hospital where his condition was stabilized using intensive care and correction of water-electrolyte and metabolic disorders. At day 9 after the disease onset, a mobile tumor-like lesion was found on palpation in the right mesogastric region. An abdominal ultrasound showed a round anechogenic lesion with distinct regular outlines (40x40 mm). A surgery was performed to eliminate jejunal obstruction with hydrogel balls. Relaparotomy was done in 6 days. Discussion: this clinical observation shows there are diagnostic difficulties that are unavoidable when a history of peroral intake of hydrogel is lacking. Being in the intestine, hydrogel granules absorbed fluid and their size increased leading to obturation intestinal obstruction. Recurrent vomiting resulted in extrarenal loss of fluid and electrolytes. The patient developed cytotoxic cerebral edema due to hypotonic dehydration. A tumour-like lesion was found on palpation at day 9 after the disease onset. Conclusions: hydrogel balls result in obturation intestinal obstruction with severe water-electrolytic disorders. This pathology requires a surgery with full revision and complete evacuation of foreign bodies from the intestine.