At least one quarter of ST-segment elevation myocardial infarction (STEMI) patients do not receive reperfusion therapy, and these patients are at high risk for new ischaemic events. We evaluated fondaparinux treatment vs. usual care, i.e. placebo or unfractionated (UF) heparin, in a pre-specified subgroup of 2867 (out of 12 092) patients not receiving reperfusion treatment in the OASIS-6 trial.