Langerhans cell histiocytosis is a rare disease entity in which various tissue are infiltrated by proliferating histiocytes. Involvement of alimentary tract is rare (<5%), especially in the stomach, Only seven cases of gastric Langerhans cell histiocytosis have been reported in Enlglish literature. Diabetes insipidus is the most common endocrinologic complication. We report a case of Langerhans cell histiocytosis involving stomach and pituitary stalk. The diagnosis of gastric Langerhans cell histiocytosis and diabetes insipidus was based on gastric mucosal biopsy specimen from a Korean man with suspicious hypertrophic gastric folds of gastric body, water deprivation test and sella MRI. (Korean J Gastrointest Kndosc 2001;22:428-430)