Hypereosinophilic syndrome (HES) is a rare condition characterised by idiopathic eosinophilia with organ system involvement. The condition is far more common in males, with a typical onset in the third to sixth decade. Cardiac damage may result in the formation of a characteristic apical thrombus readily visualised on two-dimensional echocardiography. Cardiac involvement portends a less favourable prognosis as it can be complicated by acute embolic events and progressive development of restrictive cardiomyopathy, valvular dysfunction, and heart failure. In this case report, we describe a middle-aged gentleman with HES and characteristic apical thrombus identified on contrast echocardiography. Although the use of contrast agents for assessment of left ventricular thrombus is documented in the literature,¹ this case illustrates the application of contrast echocardiography in the evaluation of eosinophilia. (Neth Heart J 2009;17:169-70.)