Rhus-related illnesses in Korea are mostly caused by ingestion of parts of the Rhus tree. Contact dermatitis occurrence after ingestion of Rhus-related food is very common in Korea. However, Rhus-related gastrointestinal disease is very rare. Herein, we present a case of eosinophilic gastroenteritis caused by Rhus ingestion. A 75-year-old woman was admitted with hematemesis and hematochezia after Rhus extract ingestion. Routine laboratory tests revealed leukocytosis without eosinophilia. Endoscopy showed friable and granular mucosal changes with touch bleeding in the second portion of the duodenum. Abdominal computed tomography revealed edematous wall thickening of the duodenum and proximal jejunal loops. Patch testing with Rhus extracts showed a strong positive reaction, suggesting Rhus as the allergen. Her symptoms improved after avoidance of the allergen.