We describe the case of a 37-year-old male referred because of hypereosinophilia associated with dyspnea. Transthoracic harmonic echocardiography showed an extensive myocardial infiltration and highlighted an intraventricular "in plus" image, whose characteristics were compatible with a diagnosis of intracardiac thrombus. The use of the myocardial contrast agent SonoVue (1 ml in bolus i.v. and 4 ml at an infusion velocity of 2 ml/min) allowed us to immediately identify, during left ventricular chamber opacification, the exact endocardial border of the left ventricular cavity and, later (when the residual SonoVue was evident only at the level of the myocardial walls), the true characteristics of the "in plus" image. This approach revealed the infiltration of the myocardial tissue and of both papillary muscles and chordae tendinae. The use of the myocardial contrast agent SonoVue may be, therefore, useful to distinguish the origin of "in plus" images often evident at echocardiography in the hypereosinophilic syndrome.