Background: Describe the outcome of adenovirus pneumonia in a pediatric intensive care unit (PICU) over a 3-year period, to identify the risk factors that may be associated with worse outcome.Methods: A retrospective observational study was performed in the PICU of children’s hospital in Shanghai from July 2016 to June 2019. Sixty-seven children over 29 days to 14 years old with adenovirus pneumonia who were admitted to PICU with acute hypoxemic respiratory failure were included in this study. The primary outcome was hospital mortality, and secondary outcomes were hospital and PICU length of stay (LOS), and risk factors of worse outcome.Results: Of 67 children with severe adenovirus pneumonia, the hospital mortality was 16.42 % (11/67) and 28-day mortality was 14.93 % (10/67). Median Pediatric Risk of Mortality III (PRISM III) score at admission was 13 (interquartile range[IQR], 10-15). Median PICU LOS stay was 11days (8-18d) and hospital LOS was 22 days (16-31d). Among children with extracorporeal membrane oxygenation (n=9), 6 cases survived and 3 cases died. The patients who need renal replacement therapy, neuromuscular blockade, parenteral nutrition, and packed red blood cell perfusion had higher hospital mortality ( p = 0.000, p = 0.041, p = 0.000, p = 0.012, respectively). Multivariate logistic analysis indicated that liver dysfunction and nosocomial infection were associated with high risk of mortality.Conclusions: The hospital mortality of adenovirus pneumonia in our PICU was 16.42%. Patients complicated liver dysfunction and co-infection & nosocomial infection were associated with poor outcome.