A 63-year-old male patient suffered an acute myocardial infarction entirely confined to the posterior wall. As symptoms persisted and cardiogenic shock developed immediate heart catheterization was performed, which demonstrated an occlusion of the left circumflex branch. Right-heart catheterization demonstrated an enlarged v-wave. Thus, acute infarct associated mitral regurgitation was suspected. In the catheterization laboratory transesophageal echocardiography including Doppler- and contrast echocardiography was then performed, which revealed the diagnosis of posterior papillary muscle rupture. The patient proceeded immediately to emergency surgery during which mitral valve replacement with a St. Jude prothesis was performed in addition to venous bypass revascularization of the occluded and a further stenosed coronary artery. The postoperative follow-up was without any complications and the patient recovered satisfactorily from the acute event. This case demonstrates the excellent diagnostic utility of emergency transesophageal echocardiography in the situation of infarct related myocardial rupture, which has to precede the life-saving operation.