Ataxia telangiectasia (AT) is an autosomal recessive immunodeficiency syndrome. The presence of telangiectasias may vary in location; however, bladder wall telangiectasias are rarely seen and may cause fatal hematuria. In the present case, a child with AT also diagnosed as acute lymphoblastic leukemia presented with persistent hematuria. In cystouretroscopy session, there have been extensive hemorrhagic bladder wall telangiectasias. Persistent hemorrhage was controlled with telangiectasia fulguration and continuous intravesical tranexamic acid infusion. As a result, we advocate early cystoscopy for patients with AT who develop hematuria and intravesical continuous tranexamic acid infusion after telangiectasia fulguration for the management of hemodynamically significant hemorrhage.