We describe four cases of eosinophilic cystitis in whom no specific cause could be found, and review the literature. Complaints at presentation included urgency, frequency, abdominal pain, and haematuria. In three patients the symptoms and ultrasound pictures suggested a bladder tumour. One patient was treated with anticholinergics and corticosteroids without relief of symptoms; a localised eosinophilic tumour was excised in one patient who remained symptom free; and two patients were managed conservatively with spontaneous resolution of bladder pathology and symptoms. One case was identified by random bladder biopsy in 150 consecutive patients with unexplained irritable micturition complaints. Eosinophilic cystitis is rare in children. After biopsy, we consider a wait and see policy is justified as symptoms tend to disappear spontaneously. Routine bladder biopsies in children with unexplained bladder symptoms is not justifiable.