The electrocardiogram was analysed in 28 adult Bantu patients with myocardiopathy and 33 with constrictive pericarditis. The over-all pattern was quite distinctive in the two groups. Patients with CP usually had sinus rhythm, notched P waves, low voltage QRS complexes in the standard and precordial leads, a normal QRS duration, no intraventricular conduction defects and a uniform and characteristic pattern of ST-T wave change in most cases. In contrast, the ECG in MCO shows left ventricular hypertrophy, varying degrees of intraventricular conduction disturbance and patterns simulating myocardial infarction