Constrictive pericarditis most commonly results from fibrosis and adhesions of the parietal and visceral pericardium due to long-standing inflammation. Common etiologies include idiopathic, post-surgical, radiation injury and infectious etiologies including tuberculosis. Traumatic hemopericardium is a rare cause of constrictive pericarditis but atraumatic hemopericardium causing constrictive pericarditis has not been reported in the literature to date. We present a case of constrictive pericarditis from an atraumatic hemopericardium after systemic thrombolysis for a massive pulmonary embolism.