Cardiac tamponade is a life-threatening predicament which demands early recognition and immediate treatment. We report a case of iatrogenic intraoperative cardiac tamponade during an orthotopic liver transplantation. A 55 year-old man was scheduled for an orthotopic liver transplantation due to hepatocellular carcinoma. During the anhepatic period, the patient's vital signs remained stable, but the central venous pressure and pulmonary artery diastolic pressure were increased. However, immediately after reperfusion, sudden hypotension and tachycardia developed. Fluid volume resuscitation and epinephrine injection led only to a transient improvement of the blood pressure. It took approximately 30 minutes to realize the possibility of the cause of hypotension might be due to cardiac tamponade rather than post-reperfusion syndrome. After an emergent transdiaphragmatic pericardiocentesis, we found that the cause of the cardiac tamponade was tearing of an epicardial coronary vein. Evacuation of a massive hematoma resulted in a rapid improvement in the patient's cardiovascular status. The patient has made an uneventful recovery.