Gastric inflammatory pseudotumors have radiographic, surgical, and histologic features that simulate malignant tumors. To avoid inappropriately aggressive therapy, it is important to know when to consider this diagnostic possibility preoperatively. The cases of two children with gastric inflammatory pseudotumors are presented to emphasize three findings in this entity: (a) An inflammatory pseudotumor should be considered if a gastric mass encompasses an ulcer or a confined gastric perforation. (b) Other unusual inflammatory responses associated with a gastric mass, such as sclerosing cholangitis and retroperitoneal fibrosis, should suggest the diagnosis. (c) Inflammatory pseudotumor is the most likely cause of a gastric mass in a child with Castleman syndrome.