A 55-year-old man was admitted for acute myocardial infarction. Cardiac catheterization revealed total occlusion of the left circumflex artery. During catheterization, he suffered cardiogenic shock. Percutaneous cardiopulmonary support was established, and the patient was transferred to the operating room. A blow-out left ventricular free wall rupture (LVFWR) with an epicardial tear, 1 mm in diameter, was found, and sutureless repair with a collagen hemostat (TachoComb) was performed. However, on postoperative day 7, echocardiography revealed an echo-free space resembling a pseudoaneurysm. A second operation was performed immediately for impending re-rupture. An epicardial tear, 2 x 10 mm in diameter, was found at the previous bleeding point where hemostasis had been achieved with only one sheet of TachoComb. The defect was closed with mattress sutures buttressed with Teflon felt. We conclude that even if the risk of re-rupture is low, sutureless repair with a collagen hemostat alone should be avoided in treating blow-out LVFWR.