There is a paucity of data regarding secondary prevention care disparities in women with premature and extremely premature atherosclerotic cardiovascular disease (ASCVD), defined as an ASCVD event at 55 years or younger and 40 years or younger, respectively. To evaluate sex-based differences in antiplatelet agents, any statin, high-intensity statin (HIS) therapy, and statin adherence in patients with premature and extremely premature ASCVD. This was a cross-sectional, multicenter, nationwide VA health care system-based study with patients enrolled in the Veterans With Premature Atherosclerosis (VITAL) registry. The study assessed patients who had at least 1 primary care visit in the Veterans Affairs (VA) health care system from October 1, 2014, to September 30, 2015. Participants included 147 600 veteran patients with premature ASCVD, encompassing ischemic heart disease (IHD), ischemic cerebrovascular disease (ICVD), and peripheral arterial disease (PAD). Women vs men with premature and extremely premature ASCVD. Antiplatelet use, any statin use, HIS use, and statin adherence (proportion of days covered [PDC] ≥0.8). We identified 10 413 women and 137 187 men with premature ASCVD (age ≤55 years) and 1340 women and 8145 men with extremely premature (age ≤40 years) ASCVD. Among patients with premature and extremely premature ASCVD, women represented 7.1% and 14.1% of those groups, respectively. When compared with men, women with premature ASCVD had a higher proportion of African American patients (36.1% vs 23.8%) and lower proportions of Asian patients (0.5% vs 0.7%) and White patients (56.1% vs. 68.1%). In the extremely premature ASCVD group, women had a comparatively higher proportion of African American patients (36.8% vs 23.2%) and lower proportion of White patients (55.0% vs 67.8%) and Asian patients (1.3% vs 1.5%) than men. Among patients with premature IHD, women received less antiplatelet (adjusted odds ratio [AOR], 0.47, 95% CI, 0.45-0.50), any statin (AOR, 0.62; 95% CI, 0.59-0.66), and HIS (AOR, 0.63; 95% CI, 0.59-0.66) therapy and were less statin adherent (mean [SD] PDC, 0.68 [0.34] vs 0.73 [0.31]; β coefficient: -0.02; 95% CI, -0.03 to -0.01) compared with men. Similarly, women with premature ICVD and premature PAD received comparatively less antiplatelet agents, any statin, and HIS. Among patients with extremely premature ASCVD, women also received less antiplatelet therapy (AOR, 0.61; 95% CI, 0.53-0.70), any statin therapy (AOR,0.51; 95% CI, 0.44-0.58), and HIS therapy (AOR, 0.45; 95% CI, 0.37-0.54) than men. There were no sex-associated differences in statin adherence among patients with premature ICVD, premature PAD, or extremely premature ASCVD. This cross-sectional study revealed that women veterans with premature ASCVD and extremely premature ASCVD receive less optimal secondary prevention cardiovascular care in comparison with men. Women with premature ASCVD, particularly those with IHD, were also less statin adherent. Multidisciplinary and patient-centered interventions are needed to improve these disparities in women.