Pneumopericardium, or air within the pericardial sack, generally occurs after high-speed blunt deceleration injuries. Although it is generally relatively benign, in rare instances, it can become hemodynamically significant. The diagnosis is easily made on plain chest radiography. More recently, chest computed tomography has been helpful in making the diagnosis. Injury to vital structures such as the tracheobronchial tree or esophageal tears require operative fixation. However, in most instances, pneumopericardium is secondary to dissection of air through the adjacent structures to the pericardial space. The air is trapped as a one-way valve. The pneumopericardium is usually self-limited, requiring no specific therapy. In patients where there is a concomitant pneumothorax, chest tube drainage suffices. We present a case of hemodynamically significant tension pneumopericardium that occurred in association with blunt carotid injury and aortic