Hemorrhagic cystitis (HC) is the main complication after hematopoietic stem cell transplantation (SCT). Adenovirus (AdV) is the leading cause of late-onset HC after SCT in Japan. The incidence and outcome of HC were studied in 77 adults who underwent unrelated cord blood transplantation (CBT). Thirty-two patients developed HC in a median of 19 days (range, 11-170 days) after CBT. The cumulative incidence of HC was 41.8% at 1 year. Ten patients developed gross hematuria. The cumulative incidence of moderate-to-severe HC was 13.2% at 1 year. Only 1 patient developed severe HC; AdV was detected in a urine sample from that patient. AdV was also detected in a urine sample from another patient with moderate HC after CBT. AdV in both patients was identified as AdV type 11. The cumulative incidence of AdV-induced HC was 2.8% at 1 year. The incidence of AdV-induced severe HC after CBT may be relatively low among Japanese adults. The role of other viruses, including BK virus, in the pathogenesis of HC after CBT needs to be examined.