The aim was to evaluate the incidence, clinical course and outcome of adenoviral infection (AdVI) in pediatric patients diagnosed and treated due to cancer and in pediatric recipients of hematopoietic stem cell. Over a 72-month period, all-in 5,599 children with cancer: 2,441 patients with hematological malignancy (HM) and 3,158 with solid tumors (ST) and 971 patients after transplantation: 741 after
allogeneic (allo-HSCT) and 230 after autologous (auto-HSCT) were enrolled into the study. Among cancer patients, 67 episodes of AdVI appeared in 63 (1.1%) children, including 45 (1.8%) with HM and 18 (0.6%; p<0.001) with ST. Within transplanted patients, AdVIs were responsible for 88 episodes in 81 (8.3%) children (p<0.001), including 78 (10.5%) patients after allo-HSCT and 3 (1.3%) after auto-HSCT. Time to develop AdVI was short, especially after allo-HSCT. The most common clinical manifestation in cancer patients was enteritis diagnosed in 63 (94.0%) cases, while among HSCT recipient asymptomatic adenoviremia was found in 36 (40.9%) cases and the most common clinical manifestation was urinary tract infection. Cancer patients with disseminated disease, as well as HSCT recipients with either asymptomatic viremia or disseminated disease, received antiviral treatment. The most commonly used first-line therapy was cidofovir. None of the cancer patients died due to adenoviral infection, while within HSCT recipients three patients developed disseminated adenoviral disease and died despite antiviral treatment. In cancer patients AdVIs are rare and associated with very good prognosis, even without specific treatment. However, in allo-HSCT recipients disseminated disease with fatal outcome is more likely to occur This article is protected by copyright. All rights reserved.