Rupture of the free wall of the left ventricle (LV) is a catastrophic complication occurring in 4% of patients after myocardial infarction (MI) and in 23% of those who die of MI. Rarely the rupture is contained by an adherent pericardium creating a pseudo-aneurysm. This clinical finding calls for emergency surgery. If no ruptures are detectable and myocardium wall integrity is confirmed, we are in the presence of a true aneurysm, which can be treated by means of elective surgery. Differentiation between these two pathologies remains difficult. We report the case of a patient with a true aneurysm, initially diagnosed as pseudo-aneurysm at our institution; we have reviewed the literature on this difficult diagnosis and outlined characteristic findings of each clinical entity.