A case of endomyocardial fibrosis in a patient with idiopathic hypereosinophilic syndrome is reported and discussed. The authors draw attention to the importance of both echocardiography (two-dimensional and Doppler) and nuclear magnetic resonance in the detection of cardiac involvement due to this rare pathology. Moreover, these imaging techniques appear to be valuable in the evaluation of effects of medical treatment. Therapy with corticosteroids alone has shown no reliable effectiveness in reducing the absolute eosinophil count. A combined immunosuppressive treatment with use of hydroxyurea is required.