Single, postoperative instillation of prophylactic intravesical chemotherapy (pIVC) is effective in reducing bladder cancer recurrences following radical nephroureterectomy (RNU). Despite high level evidence, pIVC is underutilized. Intraoperative pIVC (I-pIVC) may be easier and safer to implement than postoperative pIVC (P-pIVC). We aimed to evaluate the efficacy of I-pIVC during RNU.