Objective To determine the influence of different ages on the incidence of contrast-induced acute kidney injury (CI-AKI) in acute ST-segment elevation myocardial infarction patients after undergoing emergency percutaneous coronary intervention (PCI). Methods A retrospective study was carried out on 1 685 ST-segment elevation acute myocardial infarction patients undergoing emergency PCI and stent implantation in the ICU of our department from February 2006 to September 2012. They were divided into the ＜60 years old group (n＝932) and the ≥60 years old group (n＝753). The clinical data were compared between the 2 groups. Multivariate logistic regression analysis was used to detect the significant indicators obtained by univariate analysis to screen independent risk factors. The occurrences of major adverse cardiovascular events (MACE) and all-cause mortality were observed in 1 and 6 months, and 1 and 3 years after surgery. Results The incidence of CI-AKI was significantly higher in the ≥60 years old group than in the ＜60 years old group (14.7% vs 8.6%, P＜0.001). Age, previous myocardial infarction, and volume of contrast were independent risk factors for CI-AKI. During the 3 years’ follow-up after PCI, the cumulative all-cause mortality and cardiac mortality were significantly higher in the ≥60 years old group than in the ＜60 years old group (4.2% vs 1.5%, P＜0.001; 1.5% vs 0.2%, P＝0.011). Conclusion Clinicians should treat the elderly patients with caution, and fully assess their preoperative cardiac function and precisely determine contrast volume to prevent the occurrence of CI-AKI.