Epsilon wave is an unusual electrocardiographical finding, which may appear in other pathological conditions besides the arrhythmogenic right ventricular dysplasia, particularly in the acute myocardial infarction of the right ventricle, the inferior, or the posterior wall of the left ventricle. Its real incidence in these acute coronary syndromes remains unknown and will be probably difficult to assert, since it may be unnoticed by inexperienced physicians because of its little voltage. The outstanding interest of this case lies in the clear electrocardiographical images and in the step-by-step differential diagnosis discussed by the authors.