BACKGROUND Recent studies in animal models and humans have shown that corin is critically involved in the regulation of salt-water balance, blood pressure, and cardiac function. OBJECTIVES The goal of this study was to investigate the prognostic value of plasma soluble corin in patients with acute myocardial infarction (AMI). METHODS We enrolled 1,382 consecutive AMI patients in a prospective cohort study and explored the association of plasma corin with AMI outcomes using multivariable Cox proportional hazards analysis. RESULTS Patients with low corin levels were more likely to be female and to have histories of hypertension and heart failure (HF). Kaplan-Meier survival curves indicated that patients with corin levels above the median had a lower incidence of major adverse cardiac events (MACE) and all-cause mortality compared with those whose corin levels were below the median. Multivariate Cox regression analysis suggested that log corin was an independent predictor of MACE (hazard ratio [HR]: 0.61; 95% confidence interval [CI]: 0.42 to 0.96; p = 0.029), together with age, previous histories of AMI, HF, and diabetes, Killip class, percutaneous coronary intervention, coronary artery bypass graft, beta-blocker use, and log N-terminal pro-B-type natriuretic peptide. The C-statistic and integrated discrimination improvement for MACE were improved significantly by the addition of corin to the reference model. Moreover, log corin was also found to be a significant predictor of death (HR: 0.65; 95% CI: 0.41 to 0.97; p = 0.036) and HF hospitalization (HR: 0.48; 95% CI: 0.23 to 0.90; p = 0.009) after adjustment for clinical variables and established biomarkers of adverse prognosis. CONCLUSIONS Our study demonstrates that corin is a valuable prognostic marker of MACE in patients with AMI, independent of established conventional risk factors. (C) 2016 by the American College of Cardiology Foundation.