Objective: To determine if there is an association between fluid overload and mortality in patients hospitalized in the Pediatric Intensive Care Unit, as well as to define other risk factors for mortality in the same population. Methods: A retrospective cohort study was conducted. We included pediatric patients older than one month and under 18 years of age who were hospitalized in the Pediatric Intensive Care Unit for more than 48 hours during 2016. Demographic and clinical data were recorded. Fluid overload was calculated as [Fluid admitted (L)-Fluid eliminated (L) / weight at admission (Kg)] x 100. Poisson regression analysis was performed to determine the factors associated with mortality. Results: 171 patients were included. The median age was 31 months; the mortality was 8.2%. The Fluid Overload in the surviving population was 7.0% and 11.5% in the non survivors (p <0.05). The adjusted analysis identified Fluid overload, male gender and risk of mortality by Pediatric Index of Mortality 2 (PIM2) as risk factors. Conclusion and recommendations: Fluid overload is associated with mortality in the population of Pediatric Intensive Care Unit studied, it was found that the higher the Fluid Overload the higher the mortality rate. Likewise, it was possible to identify some non-modifiable characteristics with which mortality was increased as younger age, female gender, lower Glasgow scale score and higher Pediatric Index of Mortality 2 value; therefore, it is suggested to pay special attention to fluid management to avoid overload in those patients who comply with these characteristics, since they are more prone to mortality.