Time between emergency department (ED) presentation and treatment onset is an important, but little-researched phase within the revascularization process for ischaemic heart disease (IHD). Objective: To determine if sex influences triage score allocation and treatment onset for patients with IHD in the ED. Methods: Retrospective data for patients 18-85. years presenting to EDs from 2005 to 2010 for acute myocardial infarction (AMI), unstable and stable angina, and chest pain were analysed collectively and separately for AMI. Results: Proportionately more men (61% of males) were triaged correctly for AMI than women (51.4% of females; P<. 0.001). Across all triage categories, average treatment time was faster for men than women with AMI (P<. 0.001). When incorrectly triaged for AMI, treatment time for men was faster than for women (P= 0.04). When correctly triaged for AMI, there was no difference in mean treatment time between men and women (P= 0.538). Conclusions: Substantial undertriage of AMI occurred for both sexes, but was worse in women. Incorrect triage led to prolonged treatment times for AMI, with women's treatment delays longer than men's. When triaged correctly, both sexes were treated early for AMI, emphasising the need for all patients to be accurately triaged for this time-sensitive disease.