Background: Eosinophilic gastroenteritis (EGE), a rare disorder of unknown etiology, is characterized by eosinophilic infiltration of the gastrointestinal tract in the absence of secondary causes for eosinophilia. EGE has nonspecific symptoms, but abdominal pain, nausea, and vomiting are the most common presenting symptoms. Eosinophilic ascites is a very unusual presentation. Case presentation: A 38-year-old women at 11 weeks of gestation presented with nausea, diarrhea, and abdominal pain. Magnetic resonance imaging revealed diffuse bowel wall thickening and a small amount of ascites. Despite antibiotic treatment, her symptoms were persistent and she developed marked abdominal distension and weight gain despite antibiotic treatment. Her blood eosinophil count was high, and ultrasonography showed large ascites. Diagnostic paracentesis revealed significant eosinophilia. She completely recovered with steroid treatment and delivered a healthy baby without any complications.Conclusions: To our knowledge, this is the first case of EGE presenting with ascites during pregnancy. The serosal EGE is very rare type of EGE, but it can occur during pregnancy. The augmented Th2 immunity during pregnancy may be related with EGE.