Constrictive pericarditis (CP) following hemopericardium has been reported in the literature but its pathogenesis is open to question. Proposed mechanisms include trauma leading to damage of the mesothelial lining resulting in decreased fibrinolytic activity in the presence of blood. We present a patient who sustained blunt thoracoabdominal trauma in a car accident and subsequently developed delayed hemopericardium leading to constrictive pericarditis and impending cardiac tamponade. We performed a pericardiectomy to relieve the compression. Closely prolonged monitoring and emergent operation are suggested for such kinds of delayed complications.