Extramedullary hematopoiesis associated with fibrosis is found frequently in the liver and spleen, but seldom in other organs. Acute abdomen due to extramedullary hematopoiesis has been reported in two patients with intestinal obstruction because of heavy infiltration of the terminal ileum. This report describes the case of a 71-year-old woman with myeloid metaplasia involving the gallbladder mimicking acute cholecystitis. As far as we know, involvement of the gallbladder by extramedullary hematopoiesis has never been reported before.