2 brothers with mediastinal histoplasmosis are described. The physiopathology of the illness is reviewed with the emphasis on the antigenic theory. The pericardium is rather frequently affected during the illness, but a myocardiac involvement, which has been documented in 2 out of 3 cases, has rarely or never been reported. Considering this possibility, the authors suggest that an electrocardiography and an angiocardiography should be done before thoracotomy.