Background: The high mortality rate in patients with blunt chest trauma remains a problem. The assessment of blush in hepatic and splenic trauma is important because it indicates the need for emergency hemostatic intervention. However, the frequency and importance of blush in lung contusions are unknown. Therefore, this study aimed to evaluate the frequency of blush in the lung contusion and the relationship between blush and the clinical outcome of patients with blunt chest trauma.Methods: In this retrospective observational study, we enrolled patients with an injury severity score of 16 or higher and a chest abbreviated injury scale of 3 or higher who were admitted to the emergency department of Hokkaido University Hospital from January 1, 2003, to December 31, 2016. Blush was defined as an active extravasation image of an intravascular contrast agent recognized on contrast-enhanced computed tomography. Date of trauma severity, various treatments, and outcomes were recorded from the electrical medical records of the patients.Results: During the study period, 83 patients had severe lung contusions and 12 patients had blush. In-hospital mortality of patients with blush was significantly higher than that of patients without blush. Patients with blush required support through mechanical ventilation more frequently and for a longer duration than patients without blush.Conclusion: Our study revealed that blush in the lung contusions was not rare and was associated with a high risk of mortality in patients with severe blunt chest trauma. We should not hesitate to intervene if a blush of the lung contusion was detected in a patient with blunt chest trauma.