Arterial counterpulsation is a major advance in the treatment of myocardial Ischaemla in association with myocardial infarction. Counterpulsation is based on sound physiological principles and can be expected to limit ischaemia and necrosis when applied within the first 12 to 24 hours of infarction. It has been used in massive infarction with cardiogenic shock, and in threatening Infarction. Good results at both ends of a clinical spectrum suggest an important role throughout the spectrum. Studies in progress are attempting to define this role.