Objective To investigate the clinical characteristics of the human Adenovirus (HAdv) infections in allogeneic hematopoietic stem cell transplantation ( allo-HSCT) patients and explore the clinical significance of HAdv monitoring .Methods A total of 845 cases underwent allo-HSCT were included retrospectively in Perking University People′s Hospital from October 2012 to August 2014.Peripheral blood HAdv load were monitored twice weekly within 100 days after allo-HSCT, or whenever necessary quantitatively by real-time PCR. Meanwhile, other clinical samples such as stool , urine, and bronchoalveolar lavage fluid ( BLAF ) were also detected qualitatively whenever necessary .The follow-up period was at least six months after allo-HSCT.All clinical data were collected and analyzed .Results The total positive rate of HAdv was 3.4% ( 29/845 ) .The incidence of HAdv infection was higher in children [3.8%(6/155), <18y] than that of adults [3.3%(23/690),≥18y].HAdv infection diagnosed within 100 days after allo-HSCT accounted for 72.4%(21/29) of the total number of positive cases .There were 19 cases detected positive in peripheral blood , 16 cases in stool , 9 cases in urine , and 1 cases in BLAF , respectively.One patient was positive in peripheral blood , stool and urine.The overall median time of HAdv was 69 (13-189) d.The median time was 56 (53 -144) d in stool ,which was earlier than that of in peripheral blood , urine and stool.Among 29 cases of HAdv positive patients , 17 patients were coinfected with Cytomegalovirus(CMV) and 11 casess with Epstein-Barr virus(EBV).Twenty-five cases of HAdv were diagnosed with acute graft-versus-host disease(aGVHD) before HAdv infection, and 4 cases were diagnosed with chronic graft-versus-host disease ( cGVHD ) . The most common clinical manifestation was HAdv enteritis (14 cases), followed by hemorrhagic cystitis (7 cases).Two cases complicated with multiple organ injury ( >2 ) clinically, 1 cases with pneumonia.There were 8 cases of death at the end of follow-up.Conclusions HAdv is an important pathogen causing infection in patients after allo-HSCT. The infenction is characterized with multiple organ involvement .CMV and EBV coinfection is common .HAdv monitoring was of great significance in allo-HSCT patients.