OBJECTIVE: To explore the optimal low-density lipoprotein cholesterol (LDL-C) level in patients aged 75 years and older with established atherosclerotic cardiovascular disease (ASCVD). PATIENTS AND METHODS: We conducted a retrospective multicenter cohort study of veterans aged 75 years and older with ASCVD who were regularly hospitalized or medically examined in 15 medical institutions in southern China from January 1, 2006, to December 31, 2013. Follow-up continued through October 1, 2021. The time-weighted average (TWA) LDL-C level represented the average LDL-C level during follow-up. Participants were divided into TWA LDL-C groups of 55.0 mg/dL or lower, 55.1 to 70.0 mg/dL, 70.1 to 85.0 mg/dL, 85.1 to 100.0 mg/dL, and greater than 100.0 mg/dL. The subgroup with LDL-C levels lower than 55.0 mg/dL was further subdivided into groups with LDL-C levels from 40.1 to 55.0 mg/dL and 40.0 mg/dL or less. The association of TWA LDL-C levels with outcomes was evaluated with Cox proportional hazards models. RESULTS: Overall, 6387 patients aged 75 years or older with ASCVD were included (mean age, 79.4 years). In total, 4267 major adverse cardiovascular events, 1518 stroke events, and 515 myocardial infarction events occurred during a mean follow-up of 12.7 years. Generally, lower TWA LDL-C level was associated with a lower risk of cardiovascular events but was not associated with a higher risk of adverse events in elderly individuals with ASCVD, with the lowest cardiovascular risk observed for LDL-C levels of less than 55.0 mg/dL. After multivariable adjustment, the risk of a major adverse cardiovascular event was 1.30 (95% CI, 1.26 to 1.34; P<.001) for a per SD increment in TWA LDL-C level. Compared with TWA LDL-C levels of 40.1 to 55.0 mg/dL, TWA LDL-C levels of 40.0 mg/dL or less were associated with an increased risk of hemorrhagic stroke (hazard ratio, 3.71; 95% CI, 1.89 to 7.26). CONCLUSION: Low-density lipoprotein cholesterol levels from 40.1 to 55.0 mg/dL exhibited the maximum cardiovascular benefit in patients aged 75 years and older who had ASCVD. Lowering LDL-C levels to 40.0 mg/dL or less might increase the risk of hemorrhagic stroke.