The objective of this study was to highlight the need for investigation of antiphospholipid (aPL) antibodies in patients presenting with myocardial infarction (MI) and normal coronary arteries at angiography. We present five patients who were found to have had an MI without evidence of atherosclerosis. All had aPL antibodies and thus fulfilled the diagnosis of antiphospholipid syndrome (APS). Who did not have recurrent events on long-term anticoagulation maintaining an international normalised ratio of 3-4. This study suggests that APS is probably a major cause of MI in those with normal coronary arteries at angiography. It is an important diagnosis to make as they do not require anti-atherosclerotic treatment but appear, from this case series, to do well on high-dose warfarin. Further clinical studies are necessary to look at prevalence and best management in these patients.