A case of congenital immature gastric teratoma along with spontaneous gastric perforation in a 1-day-old boy is presented. The clinical features are similar to those of meconium peritonitis. Coincidentally, the child had an arachnoid cyst at 25 months of age. To the best of the authors knowledge, this case of congenital immature gastric teratoma associated with gastric perforation mimicking meconium peritonitis, is the first description in the English-language literature.