We present the first described case in the literature of isolated left anterior hemiblock, in the setting of massive myocardial invasion by a primary tonsilar lymphoma. Such process evolved with a morphologic pattern mimicking left ventricular hypertrophy of unequal distribution. An hemodynamic behaviour of an infiltrative cardiomyopathy, with both systolic and diastolic important ventricular dysfunction, was observed. An early presumptive diagnosis of severe lymphomatous myocardial invasion was established by echocardiography. The pathologic examination confirmed it subsequently.