We report a case of eosinophilic cystitis the onset of which was characterized by acute peritonitis secondary to a spontaneous intraperitoneal rupture of the vesical cupula. The patient was treated with urgent partial cystectomy in another hospital and 3 months later he underwent endoscopic diathermic coagulation of a residual inflammatory lesion at our institution. After an 18 month endoscopic follow-up no further signs of recurrent eosinophilic cystitis have been pointed out. The non-traumatic bladder perforation and the absence of any other bladder pathology might indicate that eosinophilic cystitis can be responsible for complete bladder rupture.