Background: Traumatic injury remains a main cause of death in the pediatric population. The pediatric trauma score (PTS) was designed to reflect the children's liability for traumas. The pediatric BIG score could be conducted immediately on admission to assess the degree of injury and to predict mortality in traumatized children. Objective: This study aimed to compare pediatric BIG score with PTS in predicting mortality in pediatric polytrauma. Patients and methods: This was a prospective comparative study conducted on 50 polytrauma pediatric cases that were admitted to the pediatric emergency department (ED). Entire cases were subjected to primary and secondary surveys. In addition, laboratory and radiological investigations were conducted. Both the pediatric BIG score and the PTS were calculated. The primary outcome was evaluated by the thirty-day mortality. Results: There was a statistically significant difference between mortality and PTS. There was a statistically significant difference between mortality and mechanical ventilation, Glasgow Coma Score (GCS) and BIG score of the studied cases. BIG score of the studied cases is statistically significant predictors of mortality. BIG score could differentiate between mortality and morbidities among the studied cases with higher sensitivity, specificity and accuracy. Conclusion: BIG score is a strong predictor of morbimortality in high-energy trauma (HET) among pediatrics. While the PTS score is also a good predictor of morbidity in pediatric HET. The BIG score presents itself as a more helpful and strong predictor because of its early and simpler calculation assets.