Background: Chest trauma, in the younger population, is considered a significant cause of morbidity and mortality. A scoring system that can give us a prediction of the thorax related complications in thoracic trauma patients is especially needed. So, the Thoracic Trauma Severity Score (TTSS) was described. The aim of this work: To assess the validity of the Thoracic Trauma Severity Score and its efficacy to predict outcome in blunt thoracic trauma patients. Methodology: Our study included 160 patients of isolated blunt chest trauma attending to emergency room at Benha University Hospital. Results: TTSS when larger than or equal 8 is a good test for prediction of outcome as sensitivity of it reaches 92.3% while specificity is 100% with 97.5% accuracy. Conclusion: This study shows how the usefulness of the TTSS for predicting outcome in thoracic trauma patients, as poor outcome was associated with higher scores.