Background: We sought to explore the sex differences in clinical outcomes among patients with acute coronary syndrome treated with ticagrelor monotherapy after ticagrelor-based 3-month versus 12-month dual-antiplatelet therapy. Methods: This was a post hoc analysis of the TICO trial (Ticagrelor Monotherapy After 3 Months in the Patients Treated With New Generation Sirolimus-Eluting Stent for Acute Coronary Syndrome; n=3056)—a randomized controlled trial for patients with acute coronary syndrome treated with drug-eluting stent. The primary outcome was a net adverse clinical event (composite of major bleeding, death, myocardial infarction, stent thrombosis, stroke, or target-vessel revascularization) 1 year after drug-eluting stent implantation. Secondary outcomes included major bleeding and major adverse cardiac and cerebrovascular events. Results: There were 27.3% (n=628) women in the TICO trial; they were older with lower body mass index and higher prevalence of hypertension, diabetes, or chronic kidney disease than men. Compared with men, women had higher risk of net adverse clinical events (hazard ratio [HR], 1.89 [95% CI, 1.34–2.67]), major adverse cardiac and cerebrovascular events (HR, 1.69 [95% CI, 1.07–2.68]), and major bleeding (HR, 2.04 [95% CI, 1.25–3.35]). Among the groups stratified by sex and dual-antiplatelet therapy strategy, the incidences of primary and secondary outcomes were significantly different and the highest in women with ticagrelor-based 12-month dual-antiplatelet therapy ( P <0.001). There was no significant heterogeneity in the impact of treatment strategy on the risks of primary and secondary outcomes between both sexes. Ticagrelor monotherapy was associated with a lower risk of the primary outcome in women (HR, 0.47 [95% CI, 0.26–0.85]; P =0.02) and comparable in men (HR, 0.77 [95% CI, 0.52–1.14]; P =0.19) without significant interaction ( P for interaction, 0.18). Conclusions: After percutaneous coronary intervention for acute coronary syndrome, women demonstrated worse clinical outcomes than men. Ticagrelor monotherapy after 3-month dual-antiplatelet therapy was associated with significantly lower risk of net adverse clinical events in women without sex interaction.