Eosinophilic gastroenteritis is a rare heterogeneous disorder of undetermined etiology that is characterized by eosinophilic infiltration of the gastrointestinal tissues and various clinical manifestations. We report an uncommon case of eosinophilic gastroenteritis involving a patient with a short history of mild upper abdominal pain, severe peripheral eosinophilia (absolute eosinophil count of > 5,000 cells per microL), and ascites. The patient was treated successfully with a course of methylprednisolone.