Time to coronary reperfusion and acute kidney injury (AKI) are powerful prognostic markers in patients with ST-segment elevation myocardial infarction (STEMI) who underwent percutaneous coronary intervention (PCI); however, no information to date is present regarding the association between time to reperfusion and AKI. We evaluated whether time to reperfusion predicts the risk of developing AKI in patients with STEMI who underwent primary PCI. Medical records of 417 patients admitted to our department from January 2008 to July 2013, for STEMI, and treated with primary PCI were reviewed. Patients were stratified by time to coronary reperfusion tertiles, and their records were assessed for the occurrence of AKI after PCI. Mean age was 61 ± 13 years, and 346 patients (83%) were men. The cut-off points for the time to reperfusion tertiles were <120, 120 to 300, and >300 minutes. Patients having longer time to reperfusion had significantly more AKI complicating the course of STEMI (3% vs 11% vs 13%, p = 0.007) and had significantly higher serum creatinine change throughout hospitalization (0.13 vs 0.18 vs 0.21 mg/dl, p = 0.003). In a multivariable regression model, time to coronary reperfusion emerged as an independent predictor of AKI and to the maximal change in serum creatinine. In conclusion, longer time to coronary reperfusion is an independent risk factor for the development of AKI in patients with STEMI who underwent primary PCI.