BACKGROUNDActivated eosinophils can infiltrate the intestinal mucosa in patients with inflammatory bowel disease (IBD), and eosinophils are also implicated in the histological damage seen in allergic diseases. AIMTo assess, in a group of patients with IBD in remission or with a mild disease activity, whether serological markers of eosinophil activation, eosinophil cationic protein (ECP) and eosinophil protein X (EPX), are related to evidence of IgE hypersensitivity and to the eosinophilia in gut mucosa. METHODSSixty-one patients with IBD (21 Crohn’s disease and 40 ulcerative colitis) in remission or with a mild disease activity were screened for IgE hypersensitivity and serological levels of ECP and EPX. Colonic biopsies were taken to assess mucosal eosinophilic infiltration. RESULTSSkin prick test were positive in 31.1% of the patients with IBD, showing skin reactions to food allergens in 17.7%. Skin prick test findings were unrelated to ECP or EPX levels, or to clinical activity or eosinophil counts in the gut mucosa. A significant correlation was found between ECP and EPX levels (r=0.77; P<0.0001). CONCLUSIONSerological ECP and EPX findings did not correlate with IgE hypersensitivity findings or eosinophilic colonic infiltration in patients with IBD in remission or with mild disease activity. The role of eosinophils in IBD needs to be better characterized in the colonic mucosa, instead of relying on serological tests.