Eosiniphilic cystitis is rare inflammatory disease of bladder that is most commonly encountered in patients with a history of allergy. Few cases were reported in literature and patients present mainly with symptoms of lower urinary tract. It rarely leads to development of a mass in bladder or thickening of bladder wall, but may be confused with bladder tumor, In this study, we presented a forty-eight years-old male patient with hematuria and radiological evidence of bladder mass mimicking bladder tumor , who was subsequently diagnosed as eosinophilic cystitis. ©2004, Fırat Üniversitesi, Tıp Fakültesi