The electrocardiographic abnormalities associated with bilharziasis are not well-known. This study, carried out in Guadeloupe, involved 220 cases of both sexes with bilharziasis, and 157 control subjects. The changes on the electrocardiogram were: an ST elevation of 0.1 to 0.5 mV associated with a large T wave in the intermediate and left precordial leads (16.8%), flattening of the T wave (13%) in V1 to V3 and beyond, a negative T wave (10.8% in the right precordial leads V1, V2, V3, and left ventricular hypertrophy (10%). The abnormalities which were found were identical to those described in the "normal" black person, and led us to discuss whether there was really a characteristic ECG for the black races. Additionally we were able to conclude that these abnormalities were unrelated to anaemia or to therapy against bilharziasis, and that there was no abnormal sex distribution. Moreover this study has revealed that the population of Guadeloupe who have no parasitic infection have ECG abnormalities (4.8%) more commonly than the white races, and has led us to suspect the possibilities of as yet underfined abnormalities which cannot be regarded as "normal".