Aims: We previously associated acute ST-elevation myocardial infarction (STEMI) with decreased plasma LL-37 levels. Therefore, this study investigated whether plasma LL-37 levels could predict ischemic cardiovascular events in patients after STEMI.Methods: We prospectively collected peripheral plasma samples and clinical and laboratory data from consecutive patients who presented with STEMI and underwent primary percutaneous coronary intervention at Fuwai Hospital between April and November 2017. Enzyme-linked immunosorbent assay measured plasma LL-37 levels, and we followed the patients for 3 years. Major adverse cardiovascular events (MACEs) were a composite of all-cause mortality, reinfarction, unscheduled revascularization, or ischemic stroke.Results: The study included 302 patients divided into high (>= median) and low LL-37 level (29.1% vs. 12.6%, p=0.0003), all-cause death (12.6% vs. 3.3%, p=0.003), reinfarction (7.1% vs. 2.0%, p=0.04), and unscheduled revascularization (13.0% vs. 5.4%, p=0.04) were higher in the low than those in the high LL-37 level group. Multivariable Cox regression analysis showed that higher LL-37 level independently predicted lower risks of MACE (hazard ratio [HR] 0.390; 95% confidence interval [CI] 0.227-0.669; p<0.001), all-cause death (HR 0.324; 95%CI 0.119-0.879; p=0.027), and unscheduled revascularization (HR 0.391; 95%CI 0.171-0.907; p=0.027). Conclusions: High basal plasma level of human LL-37 may predict lower 3-year risks of ischemic cardiovascular events in patients after STEMI.