Introduction. In children with sepsis, fluid overload as a result of an aggressive fluid replacement or excessive fluid administration may result in kidney impairment and increased mortality. Objective. To determine the association between fluid overload and the rate of kidney failure in a group of children with severe sepsis and septic shock. Population and methods. This was a prospective cohort study conducted in the intensive care unit of Hospital Universitario de Pediatría Dr. Agustín Zubillaga (Barquisimeto, Lara State, Venezuela), between March 2013 and May 2016, in children with severe sepsis or septic shock. Results. One hundred and forty-nine patients were included in the analysis. Sepsis predominated in 59.7% of cases; patients' average age was 6.4 ± 3.3 years old, their average weight was 17.8 ± 3.6 kg, 30.2% had fluid overload, and overall mortality was 25.5%. Kidney failure occurred in 16.1% of cases. A binary logistic regression model was used to identify fluid overload (odds ratio [OR]: 1.5; 95% confidence interval [CI]: 1.2-4.9, p = 0.028) and shock for more than 2 days (OR: 1.7; 95% CI: 1.3-6.3, p = 0.039) as independent predictors of kidney failure. In addition, a significant increase in the risk of mortality among children with kidney failure and fluid overload was observed as per the Kaplan-Meier method (p= 0.019). Conclusion. Fluid overload and shock for more than 2 days increase the risk for kidney failure in critically ill children with severe sepsis and septic shock.