The authors report the case of a 16 year-old boy admitted for the seventh acute occurrence in 18 months of abdominal pain associated with hypereosinophilia. Each episode was identical in nature and receded spontaneously after 5 or 6 days. Biopsy of a fiber colonoscopically obtained specimen of small intestine was performed. The diagnosis of eosinophilic gastroenteritis was based upon an infiltration of the digestive mucosa by eosinophils, the absence of elements in favor of other types of digestive-tract disease (parasitic, allergic, hematologic, or inflammatory), and the absence or other illness outside the digestive system. However, the incidental discovery of a distal dilation of both of the patients ureters during one such episode, that disappeared with the other symptoms, raises the possibility of a bladder location as well, and thus of a hypereosinophilic syndrome. Corticoids were administered then tapered down. A relapse occurred 2 months later. Currently, he is taking 20 mg of a corticoid every other day and has presented no manifestations over the last 9 months.