Résumé : Micro-Abstract The potential risk factors for viral-induced hemorrhagic cystitis in allogeneic HSCT are not well elaborated. We conducted a retrospective analysis including 64 patients who underwent allogeneic HSCT at Jules Bordet Institute. Hemorrhagic cystitis correlated to BK virus and adenovirus infection. Preventive measures for BK virus and adenovirus infections in patients undergoing allogeneic HSCT are required.