Introduction.The study objective was to analyze the Pediatric Index of Mortality 3 (PIM 3) and the pediatric Sequential Organ Failure Assessment (pSOFA) for the prediction of mortality. Methods. Observational, prospective study; patients aged 1 month to 17.9 years were included. Assessment of area under the curve (AUC) accuracy and estimation of standardized mortality rate. Results. A total of 244 admissions were studied: median age was 60 months. The main diagnoses were solid or hematologic neoplasms (26.5%). The mortality by admission was 18% (44/244). The AUC was 0.77 for PIM 3 and 0.81 for pSOFA; both scales showed an adequate calibration (p > 0.05). The standardized mortality rate was 1.91. Conclusions. We identified that the PIM 3 and pSOFA have an acceptable discrimination power. The calibration of the PIM 3 was not adequate in patients with solid or hematologic neoplasms.