The studies leading up to the unitarian concept suggesting that endomyocardial fibrosis, described in the tropics, and Löffler's endocarditis parietalis fibroplastica (Löffler's endomyocardial disease), described in the temperate zone, belong to the same disease spectrum are detailed. Evidence that the eosinophil is involved in the pathogenesis of endomyocardial diseases, irrespective of the ge...