Rupture of the ventricular septum developed three days after the onset of an acute myocardial infarction in a 57-year-old man. Nineteen days after infarction, a retrograde angiocardiogram of the left ventricle confirmed a left-to-right shunt in the septum. During cardiopulmonary bypass, the ruptured ventricular septum was repaired and an 8 × 4.5-cm aneurysmal infarction was excised. The postoperative course was uneventful, despite a small residual left-to-right shunt (1.7/1). Nine months after operation the patient was active and asymptomatic without heart-failure.