Three cases of sterile hemorrhagic cystitis following cytotoxic drugs used for childhood malignancy are described; in 2 cases associated with cyclophosphamide, vesicoureteral reflux was noted One of the cases resulted from cytosine arabinoside, not previously reported to cause hemorrhagic cystitis The roentgenologic findings are described, and emphasis is placed on differentiation from involvement of the bladder by the primary malignancy.