Acute coronary syndrome (ACS) is an important cause of mortality and morbidity in the general population. Recent advances in percutaneous coronary intervention (PCI) and optimal medical treatment have helped to improve the prognosis of patients with ACS. The previous reports indicated that women with ACS have a higher risk of adverse outcomes. However, sex differences in clinical outcomes with contemporary coronary revascularization and medical therapy for ACS have not been elucidated. We analyzed data from 676 consecutive patients with ACS (female, n = 166; male, n = 510) who were treated by emergency PCI between 2011 and 2014 at Juntendo Shizuoka Hospital. The patients were grouped according to sex. We defined major adverse cardiovascular events as a composite of all-cause death and ACS recurrence at 1 year and compared rates of major adverse cardiac events (MACE) between the groups. Women were older (75.4 ± 11.0 vs. 66.2 ± 12.2 years) and had a higher rate of multi-vessel disease, chronic kidney disease, and Killip IV at presentation. The cumulative rate of MACE at 1 year was significantly higher among women than men (17.5 vs. 10.2 %, p = 0.02, log-rank test). However, the association between women and a higher risk of MACE was attenuated after adjusting for age (HR 1.25, 95 % CI 0.77–2.00, p = 0.36) and other variables (HR 0.93, 95 % CI 0.36–2.44, p = 0.88). Adjustment for age and other risk factors attenuated sex differences in mid-term clinical outcomes among patients with ACS after emergency PCI.