80 patients with a primary myocardial infarction (32 anterior and 48 posterior) underwent cardiac catheterisation and angiography (coronary arteriography and selective left ventricular cineangiography) within 12 months of infarction. Analysis of the results of catheterisation and angiography showed: -- Diffuse coronary artery narrowing to be more frequent in patients with posterior infarction. Significant stenosis of the left anterior descending artery was observed in half these cases; -- No correlation between the results of cardiac catheterisation and the distribution of the coronary artery lesions. Changes of ventricular contraction are essentially related to the infarct size and much less to the quality of the healthy myocardium as far as can be appreciated by the usual haemodynamic methods in both anterior and posterior myocardial infarction.