Background Young women with acute myocardial infarction (AMI) have higher mortality risk than similarly aged men. An adverse lipid profile is an important risk factor for cardiovascular outcomes after AMI, but little is known about whether young women with AMI have a higher-risk lipid pattern than men. We characterized sex differences in lipid profiles and treatment utilization among young adults with AMI. Methods A total of 2,219 adults with AMI (1,494 women) aged 18-55 years were enrolled from 103 hospitals in the United States (2008-2012). Serum lipids and lipoprotein subclasses were measured 1 month after discharge. Results More than 90% of adults were discharged on a statin, but less than half received a high-intensity dose and 12% stopped taking treatments by 1 month. For both men and women, the median of low-density lipoprotein (LDL) cholesterol was reduced to <100 mg/dL 1 month after discharge for AMI, but high-density lipoprotein (HDL) cholesterol remained <40 mg/dL. Multivariate regression analyses showed that young women had favorable lipoprotein profiles compared with men: women had higher HDL cholesterol and HDL large particle, but lower total cholesterol-to-HDL cholesterol ratio and LDL small particle. Conclusions Young women with AMI had slightly favorable lipid and lipoprotein profiles compared with men, suggesting that difference in lipid and lipoprotein may not be a major contributor to sex differences in outcomes after AMI. In both men and women, statin remained inadequately used, and low HDL cholesterol level was a major lipid abnormality.