An allergic response to foreign intestinal antigens such as those contained in food has been implicated as a causative factor in the development of inflammatory bowel disease (IBD). In this study, we investigated the incidence of food allergy and other allergic disorders in Japanese patients with IBD. In addition, levels of serum IgE and IgG4 antibodies specific to various food antigens were measured. Twenty-six patients with Crohn’s dis- ease (CD) and 32 patients with ulcerative colitis (UC) were studied. Two sex- and age-matched controls were selected for each patient. The incidence of food allergy (29.2%), drug allergy (28.0%), and atopic dermatitis (28.0%) in patients with CD was significantly higher than in their matched controls (P < 0.05); however, no significant association was observed in UC patients. Levels of serum IgE specific to food allergens were similar among the groups, but the levels of IgG4 antibody specific to soybean, were significantly higher in patients with CD than in UC patients or controls. Our observations suggest that allergic disorders or dysregulation of immune responses to certain intestinal antigens can be found in CD patients in Japan in association with their disease.