Idiopathic hypereosinophilic syndrome is characterized by prolonged eosinophilia without an identifiable underlying cause and multiple-organ dysfunction, most frequently involving the heart, the central or peripheral nervous system and the lungs. We describe a case in which a patient with asthma who had idiopathic hypereosinophilic syndrome with pulmonary involvement presented with symptoms of pulmonary embolism and left ventricular thrombus.