Ataxia-telangiectasia (AT) is a hereditary recessive autosomal disorder following a course of progressive cerebellar ataxia, and oculocutaneous telangiectasia. Disease-specific telangiectasias are generally localized in the oculocutaneous region, while telangiectasias located within the bladder are rarely seen in patients with AT. The patient who had been followed-up with a diagnosis of AT since the age of 3 years was later diagnosed with acute lymphoblastic leukemia at the age of 8 years. The patient developed hematuria approximately in the 29th month of treatment. The cystoscopy revealed regions of extensive hemorrhagic telangiectasis, which was interpreted as the bladder involvement of AT. The case presented here underwent several cycles of intravesical steroid and tranexamic acid treatments and intravesical cauterization procedures, but the patient was unresponsive to all medical treatment approaches. The patient was consequently evaluated by an interventional radiology unit for a selective arterial embolization. The patient's hematuria resolved after embolization. Bladder wall telangiectasia may, on rare occasions, develop in patients with AT, and can result in life-threatening hemorrhages. We also suggest that a selective arterial embolectomy can be safely carried out in pediatric patients with treatment-resistant intravesical bleeding.