We report the association of eosinophilic gastroenteritis and eosinophilic bronchitis in a young patient with prednisone-dependent asthma and some features of lymphocytic hypereosinophilic syndrome and the sensitivity of a novel monoclonal antibody directed against eosinophil peroxidase (EPX-mAb) [4] as an unambiguous means with which to detect both infiltrating tissue eosinophils and eosinophil degranulation in gastrointestinal tract biopsies. Here, EPX is linked to eosinophilic gastroenteritis.