The aim of this study was to investigate the predictive capacity of a systemic immune-inflammation index (SII) in the detection of contrast-induced nephropathy (CIN) following ST-segment elevation myocardial infarction (STEMI). A total of 477 STEMI patients were enrolled in the study. The patients were divided into 2 groups according to CIN development. A cutoff point of 5.91 for logarithm-transformed SII was identified with 73.0% sensitivity and 57.5% specificity to predict CIN following STEMI. According to a pairwise analysis of receiver operating characteristic curve analysis, the predictive power of SII in detecting CIN following STEMI was similar to that of high-sensitivity C-reactive protein and better than the neutrophil/lymphocyte ratio or platelet/lymphocyte ratio. As a result, SII can be used as one of the independent predictors of CIN after STEMI.