Among patients with ST-segment elevation myocardial infarction (STEMI) and aged < 60 years, women have worse outcomes than men, according to data from the ISACS-TC registry. This sex-specific difference declines with increasing age. A total of 2,657 women and 6,177 men were hospitalized and treated for STEMI in 41 hospitals in 12 countries between 2010 and 2016. Among these patients, 30-day mortality was significantly higher in women than in men (11.6% versus 6.0%). Mortality remained higher in women than in men in the group of patients who underwent percutaneous coronary intervention (PCI; 7.1% versus 3.3%). After multivariable adjustment, women aged < 60 years had a higher risk of early mortality than men in the same age group (OR 1.88, 95% CI 1.04–3.26). The risk was not significantly different between the sexes in those aged ≥ 60 years. The investigators highlight that the differences in STEMI mortality between younger men and women were unrelated to disparities in treatment, given that a difference was observed even in those undergoing primary PCI.