Acute kidney injury (AKI) is a common complication among patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI), and it is associated with poor long-term clinical outcomes. No studies have yet evaluated the association between cardiac function and the risk of AKI in this patient population. We conducted a retrospective study of consecutive 386 patients with STEMI who underwent primary PCI and had a full echocardiography study performed within 72 hours of hospital admission from June 2011 to December 2013. AKI was defined as an increase of ≥0.3 mg/dl in serum creatinine within 48 hours after admission. Thirty-four patients (9.7%) developed AKI. Echocardiography demonstrated that patients with AKI had significantly lower systolic ejection fraction (EF; 48% ± 8% vs 41% ± 10%, p <0.001), lower septal (p = 0.001) and lateral (p = 0.01) e′ velocities, higher average E/e′ ratio (p = 0.006), elevated systolic pulmonary artery pressure (p <0.001), and higher right atrial pressure (p = 0.001). In multivariate regression analysis, left ventricular EF emerged as an independent predictor of AKI (odds ratio 1.1, 95% confidence interval 0.86 to 0.96; p = 0.001) for every 1% reduction in EF. In conclusion, among patients with STEMI undergoing primary PCI, left ventricular EF is a strong and independent predictor of AKI.