A man with dilated cardiomyopathy presented with decompensated heart failure and marked eosinophilia. After extensive clinical and laboratory evaluation for hypereosinophilic syndrome, including a myocardial biopsy, it was determined by means of rechallenge (second dobutamine infusion) that the patient was afflicted with dobutamine-induced eosinophilia. This report is important because of the high utilization rate of this drug in a sick population. Simply discontinuing it or switching to another agent can avert the high cost and risk of the evaluation for hypereosinophilic syndrome in this compromised group of patients.