A normal coronary arteriogram after transmural myocardial infarction is a well-recognised phenomenon, but the pathophysiology remains unclear in most cases. A possible aetiological role of oral contraceptives is suggested by the occurrence of unequivocal myocardial infarction with normal or near normal coronary arteries in 4 young women who had been taking oral contraceptives. While the cause-effect relation of coronary thrombosis and myocardial infarction remains controversial in patients with coronary atherosclerosis, a primary occlusion of macroscopically normal coronary arteries by cellular elements of blood appears possible in these cases. The action of contraceptives, the, would be analogous to their thrombogenic effect in peripheral veins and cerebral arteries. Absence of atherosclerotic lesions in these patients favours spontaneous thrombolysis and restoration of normal vessel patency in many of these cases. Myocardial blood flow in the region of the damaged left ventricular wall remains low in spite of normal coronary arteries. Reduced perfusion in infarcted areas is assumed to be the consequence of structural and functional alterations at precapillary and capillary level rather than an effect of obstructive coronary disease.