Eosinophilic gastroenteritis is a rare disease of unknown cause characterized by eosinophilic infiltration in various areas of gastrointestinal tract with gastrointestinal symptoms such as abdominal pain, vomiting, diarrhea and rarely ascites. Its clinical feature depends on the type of layer and location involved. Serosal eosinophilic infiltration, the rarest form of presentation, may result in development of eosinophilic ascites. We experienced a case of eosinophilic gastroenteritis involving entire gastrointestinal tract with eosinophilic peritoneal fluid in a 38-year-old female with abdominal distension and abdominal pain, Upper gastrointestinal endoscopy, colonoscopy, small bowel series, abdominal CT showed diffuse wall thickening from esophagus to rectum. The eosinophilic peritoneal fluid and peripheral eosinophilia were confirmed by multiple biopsies of the gastrointestinal tract, She was treated with corticosteroid and responded dramatically. We report this case with a brief review of the literatures. (Korean J Gastrointest Endosc 2001;22:159 - 163)