Abstract 1. (1) The criteria generally accepted for the diagnosis of cardio-pulmonary schistosomiasis are given. 2. (2) In Rhodesia where schistosomiasis is endemic, chronic cor-pulmonale is not uncommonly seen amongst Africans, but not in all cases are these requirements for a diagnosis of schistosomal cor-pulmonale fulfilled. 3. (3) Three cases of cor-pulmonale are described to illustrate this point. All three were alike clinically but only one provided the desiderata for a diagnosis of schistosomal cor-pulmonale. 4. (4) In an endemic bilharzial region one should be careful not to label a patient as suffering from schistosomal cor-pulmonale even if ova are present in the excreta. 5. (5) It may also be argued that even if ova are present in the lungs of a patient presenting with the features of chronic cor-pulmonale, these may be coincidental to a disease of the pulmonary arterioles quite apart from schistosomiasis.