We report two cases of eosinophilic cystitis in children of 11 months and 11 and a half year of age respectively. The presenting symptoms were the emision of mucosanguinolent filaments in the urine in one case and with lower urinary tract symptoms and macroscopic hematuria in the other. Physical examination revealed in one of them a round, tough and painful mass in the hypogastric area. In one case we found peripheral blood eosinophilia. They both showed in the Urinalysis albuminuria, pyuria and hematuria, with the presence of eosinophils in one of them. Macroscopic examination presented in the two cases a tumoral, mamelonne mass in the wall of the bladded. The diagnosis was anatomopathologic due to the demonstration of an inflammatory infiltration, primarily of eosinophils. The clinical course was unfavourable in the case an hemicystectomy was practicated and self-limited in the one only symptomatic treatment was used.