Myocardial free wall rupture is the most serious complication of acute myocardial infarction. Although it is not uncommon, it is difficult to treat successfully. We report a case of acute inferior myocardial infarction complicated with left ventricular free wall rupture that occurred 8 hours after onset of chest pain. In this case, progression of mild pericardial effusion to cardiac tamponade was monitored by transhtoracic echocardiography. Pericardiocentesis and draninage failed to treat cardiac tamponade, and surgical repair was performed successfully. The patient discharged uneventfully on 28th day and followed regularly at the outpatient department.