Eosinophils are associated with various disorders, such as allergic or hypersensitivity reactions, parasitic diseases, connective tissue diseases, certain neoplastic diseases (Hodgkin's disease, lymphomas, and carcinomas), and various immune deficiency states. Eosinophils can infiltrate any tissue and can cause tissue damage. Heart, has been demonstrated to be the most extensively involved and toxicity of eosinophils is well-established on cardiac tissue. We describe 3 cases with extensive eosinophilic infiltration without endomyocardial fibrosis. All patients died after a short clinical course with rapidly progressive heart failure. Bronchial asthma, hydatid disease and drug reaction were considered as possible etiologies of eosinophilia in case 1 and case 2. Case 3 was considered to fall into the "idiopathic hypereosinophilic syndrome" in which no underlying causes for eosinophilia could be identified.