Background <p>Eosinophilic cystitis is a rare disease of the bladder which is difficult to distinguish from other causes of haematuria, and is often misdiagnosed number of times. Diagnosis is made with bladder biopsy. Early diagnosis is important as it is life threatening condition secondary to ongoing hematuria.</p> Case presentation <p>We report the case of a 26-year-old female presents with sudden onset of gross haematuria since 1&#xa0;day and hypovolemic shock at time of presentation. Cystoscopy showed bladder clots and patchy areas of cystitis with diffuse urothelial erythema. Bladder biopsy revealed lamina propria with inflammatory infiltrate rich in eosinophils. After diagnosis she was commenced on medical treatment with complete resolution of symptoms.</p> Conclusion <p>Early diagnosis is important as it is life threatening condition secondary to ongoing hematuria and is done through a combination of surgical and nonsurgical methods such as bladder biopsy. Once diagnosed, the treatment is by the combination of conservative management and operative interventions. Natural history of this entity is difficult to predict as there are number of other common causes of hematuria which if not treated may result in bladder damage, upper tract damage and can be life threatening as in our case. This case highlights the importance of investigating hematuria that is unresponsive to initial hydration and bladder irrigation. It is important for urologist to think of this entity and also obtain a diagnosis, leading to definitive treatment.</p>