Blunt traumatic cardiac rupture is rare and associated with high mortality. The most popular theory of cardiac rupture after blunt thoracic trauma is rapid deceleration with disruption of the atria from their connections to the vena cava and pulmonary veins. In cases with both massive hemothorax and hemopericardium, injury can usually originate from the heart and/or major vessels. Surgical approach through the median sternotomy can provide convenience to repair the defect. In this article, successful treatment with median sternotomy of a 33-year-old male case with a rupture of the left atrium after blunt thoracic trauma was reported.