Left ventricular free wall rupture (LVFWR) is a grave complication of acute myocardial infarction (MI). We report a case of a 73-year-old male who developed LVFWR five days after a transmural MI. The diagnosis was confirmed with echocardiography, which showed a large pericardial effusion with a clot in the pericardial sac. This case emphasizes that a high index of clinical suspicion for the acute mechanical complications of MI should be present when managing patients with transmural MIs. In addition, stat echocardiography is necessary to diagnose LVFWR and initiate treatment.