A 60 year old woman presented with an inferolateral myocardial infarction (MI) which was treated with thrombolytics and complicated by heart failure. Transthoracic echocardiography identified a large left ventricular (LV) pseudoaneurysm and coronary angiography demonstrated an occluded circumflex artery. Cardiovascular magnetic resonance (CMR) was performed before surgery. CMR showed a 5.7 cm × 8 cm × 10 cm (right-to-left by anteroposterior by cephalad-caudad) posterolateral LV pseudoaneurysm with a wide neck in free communication with the basal LV cavity (panels A–C). The pseudoaneurysm split the wall between the posterior mitral valve leaflet (PMVL) and its supporting papillary muscle. Cine images showed reduced long axis function and there was thinning and akinesis of the remaining basal anterolateral and inferolateral wall (to view video clip visit the Heart website—http://www.heartjnl.com/supplemental). Early gadolinium enhanced CMR detected thrombus within the pseudoaneurysm while late gadolinium enhanced CMR demonstrated enhancement within the wall of the pseudoaneurysm and surrounding akinetic segments indicative of MI. This case illustrates the role of CMR with gadolinium enhancement for providing valuable structural and functional information in the pre-operative assessment of LV pseudoaneurysms.