['Moderate renal impairment (RI) with a glomerular filtration rate (GFR) <60 ml/min/1.73 m2 is known to predict survival. The authors investigated whether mild RI with an estimated GFR of 60-89 ml/min/1.73 m2 independently predicts survival in a contemporary population with ST segment elevation myocardial infarction (STEMI).', 'This is a single-centre, observational, retrospective cohort study. Patients 601 patients with STEMI who underwent emergency catheter laboratory admission met the inclusion criteria for this study.', 'Estimated glomerular filtration rate (eGFR) was obtained by the Modified Diet in Renal Disease equation, and preprocedure renal function was subdivided into chronic kidney disease stages. Univariate and multivariate Cox regression analyses were performed to assess which of 17 patient or procedural variables were independent risk factors for death.', 'Longitudinal data were collated for 576 patients (96.3%). Median follow-up time was 2.6 years. 30-day and long-term death rates were 5.7% and 12.5%, respectively. Following multivariable analysis, mild RI with an eGFR of 60-89 ml/min/1.73 m2 was a strong independent predictor of death, compared with an eGFR ≥90 ml/min/1.73 m2 (HR 2.79, 95% CI 1.98 to 3.92, p<0.001), and increasing chronic kidney disease stage was a strong predictor of death after both 30 days and long-term follow-up. An eGFR of 60-89 ml/min/1.73 m2 had a greater independent effect on short- and long-term mortality than the presence of diabetes mellitus (HR 2.0, 95% CI 1.2 to 3.33).'] Is mild chronic kidney disease an independent predictor of long-term mortality after emergency angiography and primary percutaneous intervention in patients with ST-elevation myocardial infarction?