A 2-month-old girl was seen by the paediatric surgeon for massive vomiting and a prenatally diagnosed abdominal cyst. A 13-year-old girl, who had been vomiting increasingly for some weeks and was losing weight, was found to have a cyst that appeared to be situated within the gastric wall. Surgery revealed gastric duplication cysts in both children. Duplication cysts are rare, congenital deformities of the gastrointestinal tract. Only 9% originate from the stomach. The symptoms depend on the location; some cysts may remain silent for a long period. Complete excision of the cyst wall is mandatory because of the risk of malignant degeneration.