SummaryBilateral ligation of the internal mammary arteries was performed on 35 patients. Most of them had their first heart attack many years ago. In those patients the ECG as well as the clinical symptoms were stabilized leaving a slight cardiac insufficiency.Results may be recorded as follows : excellent : 23 %; fair or good : 51 %; no change : 26 %.The method appears as valuable. The results do not seem to originate in a psychological action, but seem to depend on the effect of the anastomosis between the coronary system and the pericardio-phrenic branches of the internal mammary arteries, the existence of which was experimentally demonstrated.Even if the amount of blood provided by this anastomotic route does not exceed one or even one half ml blood, it may help to decrease the myocardic ischaemy as it is shown by the coronarographic studies that the whole arterial tree has a capacity not exceeding 4 to 6 ml.This explanation, though still hypothetical, seems to be the more plan sible in the present state of the question.