Background: In clinical practice, heart failure often occurs after acute myocardial infarction, and a new biomarker for its early prediction is urgently needed. The aim of this study was to investigate the relationship between serum iron and heart failure after acute ST-segment elevation myocardial infarction (STEMI).Methods: A total of 41 patients with heart failure after STEMI and 31 controls were included in the study. The demographic variables and baseline clinical characteristics of both groups were analyzed.Results: There were no significant differences between patients with heart failure and controls in terms of demographic characteristics. There were significant differences in terms of serum iron, N terminal pro-B-type natriuretic peptide levels, left atrial diameter, and left ventricular ejection fraction. Binary logistic regression analyses demonstrated that serum iron (odds ratio [OR]: 0.804, 95% confidence interval [CI]: 0.699-0.924) and Tn-I (OR: 1.072, 95% CI: 1.011-1.137) were independent predictors for heart failure (p < .05, respectively). Receiver operating characteristic analysis showed that the area under the curve for serum iron was 0.808 (95% CI: 0.707-0.908, p < .01). The best cutoff value of serum iron was 11.87 μmol/L (sensitivity: 87.1%; specificity: 68.3%).Conclusions: Patients with heart failure after STEMI have lower serum iron levels than patients without heart failure after STEMI. Serum iron levels are a risk factor for heart failure after STEMI.