Acute kidney injury(AKI)was a risk factor for poor outcomes in patients with ST-segment ele-vation myocardial infarction(STEMI).Whether postoperative serum creatinine(SCr)level measured at early time(24 hours)after percutaneous coronary intervention(PCI)had prognostic role in elderly patients with STE-MI was unclear.Methods SCr was measured within 24 hours after PCI.A total of 883 elderly patients(≥60 years)with STEMI were finally included and divided into three group according to the tertiles of postoperative SCr level(umol/L):＜81(n=283),81-107(n=302)and≥107(n=298).The relationship between postoperative Scr and in-hospital and 1-year adverse events was evaluated.Results In-hospital mortality was 5.4％(48/883),which was significantly higher in patients with a high postoperative SCr level(1.8％vs.3.0％vs.11.4％,P＜0.001).Receiver operator characteristic curve analysis indicated that postoperative SCr＞120 umol/L had a sensi-tivity of 66.7％and specificity of 79.2％for predicting in-hospital death[area under the curve(AUC)=0.768,95％CI:0.697-838,P＜0.001].Multivariate analysis showed that postoperative Scr＞120 umol/L was an indepen-dent risk factor for in-hospital mortality even after adjusting for the baseline renal dysfunction[estimated glomer-ular filtration rate(eGFR)＜60 mL/(min ? 1.73 m2)].Kaplan-Meier analysis showed that patients with postopera-tive SCr＞120 umol/L had a higher one-year mortality than those without(Log-rank test:57.8,P＜0.001).Conclu-sions SCr level measured within 24 hours after PCI could serve as an early and powerful marker for predicting in-hospital and one-year mortality in elderly patients with STEMI.