Case 1: 67-years-old woman with pollinosis noticed oppressive feeling of chest and back, and heart burn after accidental ingestion of her dental filling and dental treatment. Oral famotidine did not improve her symptom. Her peripheral blood eosinophils increased to 38.0%. As for the specific IgE, only cedar and cypress were positive. Case 2: a 42-years-old-woman with pollinosis and asthma repeated urticaria, heart burn, diarrhea and peripheral eosinophilia (25%). At her first visit to our department, her blood eosinophil increased to 52.9%, her serum IgG markedly increased in polyclonal pattern and overt all subclasses. The specific IgE was positive only for cypress. Because they revealed a remarkable infiltrates of eosinophils in the mucosa of alimentary tract, we diagnosed the 2 patient as eosinophilic gastroenteritis. In case 1, based on the history and patch-test-positive finding of formalin and 2-hydroxyethyl methacrylate, we diagnosed the two may be causative allergens. In case 2, based on the patch-test-positive finding of garlic and sesame and improvement after removal of the two allergens, we diagnosed the two may be causative allergens. Although causative allergens of eosinophilic gastroenteritis are almost unknown, some cases are reported to be determined the allergens of foods and drugs. In our cases, patch test was useful to identify the allergens.