Aims & Objectives: To evaluate the outcomes of patients with severe sepsis and septic shock who receive fluid resuscitation with balanced and unbalanced solutions. Methods: Design:An observational analytic prospective cohort study. Patients: Patients between 1 month and 17 years of age, with severe sepsis and septic shock, admitted to the pediatric intensive care unit at the Fundación CardioInfantil-IC, who required a fluid bolus with balanced or unbalanced solutions due to hemodynamic instability within 72 hours of admission. Results: Of the 1,074 admissions to the pediatric intensive care unit during the study period, 103 patients had severe sepsis and septic shock with all inclusion criteria. The median stay was 7.5 days (IQR 3.2-21.0) and the median age was 15 months (IQR 6-1 – 86.4). The most frequent infection were respiratory and gastrointestinal (54.4% and 24.3%). Acute kidney injury was seen less frequently in children who received a balanced solution compared to those who received unbalanced solutions (19.4% vs 47.2%; p=0.03 aOR, 0.27; 95%CI, 0.11-0.67), adjusted for disease severity. The group which received balanced solutions required less continuous renal replacement therapy (CRRT) (3% vs 16.7%; p=0.02) and had a lower mortality at 28 days (7.6% vs 25.7%; p=0.02) compared to the unbalanced solution group. We don't found differences in the frequency of metabolic acidosis (p=0.84) and hyperchloremia (p=0.12). Conclusions: In children with severe sepsis and septic shock, the use of unbalanced solutions for fluid resuscitation is associated with a greater frequency of acute kidney injury, need for CRRT and a lower survival compared with balanced solutions.