Gastric carcinoma is an extremely rare cancer in children. A case is presented of a 9-year-old boy admitted to The University Hospital Brno with a 4-month history of abdominal pain, anorexia, weight loss, nausea, and vomiting. Several of his family members died from or have been treated for cancer. Barium meal examination performed 2 months prior to admission was nondiagnostic. When gastroendoscopy, laparoscopy, and abdominal computer tomography scan were performed, the diagnosis of adenocarcinoma of the stomach was established. The patient died 10 days after admission because of rapid cancer spread. Miliary metastases of the peritoneum, mesenterium, omentum, liver, bowels, lungs, heart, bone marrow, and skin were found. No penetration through the hematoencephalic barrier was noticed.